Port forwarding is used when a certain program, server, games console or device requires that a specific signal is routed through. For example, a wireless CCTV camera may require a signal on a specific port to be routed through to that device when you try to connect externally from a device such as a Smart Phone or Tablet.
Some programs require a port is open as they will listen on this custom port for communication channelled directly to them.
These programs are too numerous to mention here, so we recommend you first take a look at http://portforward.com/
This is a vast online resource of routers, ports and applications that use them. You can often find specific information for a particular program, and how to open the port that is required.
Remember also, if you are setting up port forwarding to a physical device, such as another PC or wireless camera, and this has an IP address provided via DHCP from the router, when the router is rebooted, the internal address of the device may change. This can upset the port forwarding rules you have set in the router, and stop it from working. To avoid this, you can ‘reserve’ an IP address for that specific device.
To reserve an IP address
Log into the router by typing 192.168.1.1 in your internet browser. When prompted for a password, the user name is ‘admin’ and the password is ‘admin’.
If you have the TalkTalk super router, you can skip the next step.
Click Advanced from the menu on the left hand side, and click ‘OK’ when you see the warning box for advanced users appear.
· Huawei HG 533 router.
Select the ‘Basic’ option and then ‘LAN’. Under the DHCP tab, then at the bottom of the screen, you can see the option for IP address reserve.
Click ‘New’, select or enter the MAC address of the device. Choose an IP address to reserve and then submit. It is always good to set a high number as it will be easier to remember, for example 192.168.1.100 etc.
D-Link 3680 & 3780
Select LAN Setup, locate DHCP Table, enter your device details and set the IP address as ‘Static’
Select ‘Home Network’ from the top menu bar. Select ‘LAN Interface’ from the Home Network Section. Under DHCP reservation, click ‘Create new static IP address’. Select your device or enter the device details and Save the settings when completed.
To Open or forward a Specific Port Number or Port Range
Huawei HG 533
Select ‘Advanced’ then ‘NAT’ then select the Port Mapping section and enter your port number details. If you only wish to open a port without forwarding to a specific device, you can leave the internal host field blank, otherwise enter the IP address of the device.
D-Link 3680 & 3780
Select ‘Advanced’ from the top menu bar, then select ‘Virtual Server’. Enter your port numbers, and if you require the port forwarding to a specific device or PC, you can enter the IP address in the Internal IP field.
TalkTalk Super Router (Huawei HG 635)
Select ‘Internet’ from the top and then select ‘Port Forwarding’. Under Port Mapping, select ‘New Port Mapping’
Enter a name for this rule in the Mapping Name field. Choose your application and if your application is not listed, click ‘Add port mapping application’. At the bottom of the application list is an option for ‘New’. Enter the name of the application, and enter the start and end ports you wish to open. Then click Save.
You can then specify a device an internal host . You can choose from any previously connected devices in the list, or Add a new device.
If you only wish to open a port, you can select ‘New Port Trigger’ and enter the port details.
Always remember to ‘Save’ when you add or change any details.
Maintenance or recovery mode is useful to reset your TalkTalk TV box, but you should only use this option after all other diagnostics have been completed.
If your TalkTalk TV box is stuck booting up after switching it on, or is failing to respond to the remote control or any manual button combinations, you should power off your TV box (via the button at the back of the TalkTalk TV box) and wait for a few minutes before switching it back on again.
When powered back on, if the box displays the same behaviour, you should follow the below steps:
Ensure the TalkTalk TV box is turned off and connected to the broadband router (using a cable or Powerline adapters).
Power on the TalkTalk TV box using the button at the back.
Instructions for entering Maintenance Mode.
If you have a box with recording capability press the power (standby) button on the front panel, then quickly press and hold both the + and – buttons at the same time.
If you have a box that doesn’t record, press and hold both the + and – buttons at the same time and then press the power (standby) button, whilst continuing to hold the + and – buttons. NOTE: If you see the "Please wait…" message you'll need to try again.
Once the "Huawei – Maintenance Mode menu" is displayed, let go of the + and –
The + and – buttons on the front panel will navigate the menu. Use those buttons to highlight the option as recommended below:
If you’re trying this for the first time on a box that records, select Factory Reset Keep recordings
If you’ve already tried a Factory Reset Keep recordings but the box still won’t boot up, select Factory Reset Delete recordings
If you have a box that doesn’t record select Factory Reset.
Press the power button on the front panel to select the relevant option. This will bring up some information and ask "Do you want to proceed?". Press the power button again to confirm.
Your TV box will now reinstall the latest software, this may take several minutes. Once complete, the box will restart.
Once restarted, the TalkTalk TV box will show the initial setup wizard. You’ll need to run through the setup wizard including tuning the channels.
If you're still experiencing issues after completing maintenance mode reset, then you can contact our TV colleagues here.
Step 1: Check if Your Connection is Physically Dropping
Is the ADSL light on the router flashing or going off. If not, are you using wireless? A dropping wireless connection is actually different than a dropping broadband connection, and you should always check your broadband with a wired connection where possible.
Disable the ‘Time Out’ feature on your router. Most routers will default to time out after 30 minutes of inactivity. The ADSL light will remain solid, but you may notice the internet light turns red.
To disable this feature, firstly you will need to log into the router.
· Open a browser, and enter the address 192.168.1.1
Next, login with the username : admin and the password : admin
Click ‘Advanced’ from the Menu on the left, then click OK when presented with the warning box.
If you have a HUAWEI model of router, then the Idle Time Out option can be found under the ‘Basic’ option, then under the ‘WAN’ option. Near the bottom of the page, you will see Idle time. Set this to 0 for always on.
· If you have the HG635 'Super Router' then the option can be found under 'Internet', then under 'Internet Connection', click 'Edit' under 'Internet DSL', and near the bottom of this section you will see the option for 'Always Online'. (This option is not applicable if you have Super Powered Fibre broadband).
· If you have a D-LINK 3780 model, the option for ‘Always on’ can be found at the bottom of the page under ‘Internet Setup’ from the menu on the left.
· The D-LINK 3680 or 2640r model, the option for ‘Idle Time Out’ can be found half way down the page, under ‘ADSL Setup’ from the menu on the left.
Older models may also show the option as ‘Always on’ or ‘Nailed Up Connection’.
Remember to ‘Submit’ or ‘Apply’ any changes to ensure they are saved.
Step 2: Check Your Phone Line
Even if you do not use your phone, the broadband shares the same line, so always connect a phone, and listen for any noise or crackling. Any noise on the line may be the cause of the dropping connection.
Step 3: Check for Unfiltered Devices
If you have more than one phone socket in your home, check for any phones or other devices that are connected to the phone line without a filter. An unfiltered phone is one of the more common causes of a dropping connection.
Here’s how your micro filter should be connected
Test your connection at the Test Socket if you have one. (Not required if you are on Super Powered Fibre Broadband)
If your main socket looks like the picture below, then it will have a Test Socket inside.
Step 4: Factory Reset Your Router
The router could have a software glitch which a factory reset may resolve. Before you do this however make sure you have a note of your broadband username and password as you may need to put these back into the router.
Step 5: Check Your Router Filter and Cables
A faulty micro filter, router or ADSL cable may be the problem. If you do not have access to test with another router, then check to see if you have a friend or family member that can test these for you on their connection. Even if they look ok, a faulty filter can cause a connection to drop, and can quickly be changed.
Faulty cables, such as the ADSL cable, or even a faulty Ethernet cable can have a small break inside, often referred to as a micro fracture, and this can cause the connection to drop.
Switch off any nearby electrical equipment that may cause interference, especially any devices connected to the same power socket as the router. These can include Televisions, power adapters, Christmas tree lights, microwaves etc.
Try the router at a different power socket. In very rare cases, there can be poor earth in a household electrical circuit that can cause RF interference. If this was the case, you can purchase an electrical extension lead with a built in mains filter.
You can carry out a basic check for electrical interference. If you have an old AM/FM radio (not DAB) you can tune the radio to MW 612 KHz and listen for any interference on the signal. This is a similar frequency to the ADSL signal and can be a good indication of any nearby by electrical devices causing the fault. If you holde the radio close to an active TV screen, you will hear a distinctive noise, if you move about half a metre away, this will stop. You can check to see if this interference noise is coming from other devices near the router of phone socket.
If you notice the broadband drops at specific times, it is always good to consider there may be interference coming from any electrical device near the path of the line from the house to the exchange.
If your connection does drop at a particular time each day, consider, is there anything directly outside your home that could cause this, such as faulty street lighting or inside, such as faulty central heating timers.
So as you can see, there are many things to consider when troubleshooting an unstable broadband connection, but if you follow these main steps, this can help rule out the majority of common causes.
Here at TalkTalk, we know that sometimes our customers prefer to use their own router, and some may encounter difficulty when setting this up.
We will offer a little help and guidance for setting up the most commonly used models of router here, but as there are so many different makes and models, we can’t list them all.
As long as you know the main options to look for in the router set up pages, the following information should help.
Before Setting up your Router
Firstly, before setting up any router you’ll need your:
Broadband connection user name
This will usually be if the form of … firstname.lastname@example.org and the password will usually be a series of letters and numbers.
If unsure of your broadband username and password, you can call an automated password line from your TalkTalk home phone, this will read the details to you. The number you need is 0870 087 5562.
Now whichever router you have, it will either have a set up wizard or it will require manual setup, however the information required will usually be the same.
Here is the core information it will ask for. Don’t worry if your router does not ask for all this information, sometimes it can be automatically detected ( please note- if you are a TalkTalk TV customer you will also need these settings)
IP Address : Dynamic (Provided by ISP)
VPI : 0
VCI : 38
MTU : 1432
DNS Setting : Set this to Automatic
Encapsulation : PPPoA (VCMux)
Modulation Type : Auto
Multiplexing Method : VC-Based
If the router has an ‘Idle Timeout’ option, we suggest this is set to 0 whenever possible to keep the router ‘always on’.
Setting up your Router
To set up a router, you should have a PC or Laptop connected directly to the router via Ethernet cable.
· Open a browser program, usually Internet Explorer or Google Chrome
· Type in the address of the router. You may also be asked for a username and password. Below is a table of the more common router addresses, usernames and passwords if required.
Netgear model routers are popular with many customers, and the setup options are very similar between models.
The most common settings layout will have a menu on the left hand side, and will have a Set up wizard option or a basic settings option to manually enter the details.
As you can see, most of the information can be entered under the Basic Settings option.
TP-Link models are becoming more popular these days, as they have an excellent wireless range.
· When logging into the router, you will see a ‘Quick Start’ option. This is the setup wizard that will guide you through the setup and ask for the common options we mentioned earlier
Belkin router setup pages are similar between models, and the details can be entered under Internet WAN > Connection Type. Some older models may only allow you to select PPPoE as the connection type, however don’t worry, this will work also.
The main options are listed under Network Setup, and as you can see below, most of the required options are automatic. Once you have selected the encapsulation, the only other details required are the username and password for your broadband connection.
As you can see from the four examples above, as long as you have the required information mentioned earlier, then setup should be straight forward.
All routers will have different advanced options, firewall settings etc, and are too numerous to mention, so if you have a specific requirement or specific model in mind, we always recommend asking our community.
By default, most ADSL routers are set to go into standby after 30 minutes of inactivity. This does not affect Fibre routers, as Fibre optic connections are always on.
If not using the internet for 30 minutes or more, you may see the internet light go red, and it can give the appearance that the internet has dropped or disconnected. Opening a web browser, and typing in a web page, will usually ‘wake’ the router, but if using wireless devices, this can sometimes cause the wireless connection to time out and disconnect.
You can set your router to ‘Always on’, or in some older routers this may be referred to as ‘nailed up connection’. To change this setting, you will need to log into the router, preferably with a device that is connected ‘wired’, ie. A PC or Laptop.
Logging into your Router
Open a web browser, and type in 192.168.1.1
When asked for a username / password this is admin for both. Note: On our newer routers, the password will be found on a sticker located on the bottom of the router
For all routers apart from the Fibre Super Router, click Advanced, and click OK to the warning box regarding advanced users. This will give access to the router settings menus.
Click Basic then WAN Settings from the left hand menu.
Scroll down to Connection and click on ‘Nailed Up Connection’, then click Submit.
Click BASIC then WAN from the left hand menu.
Scroll down to the ‘Connection Trigger’ and select Always On from the drop down menu.
Click Submit to save the settings.
Click BASIC then WAN from the left hand menu.
Go down to Dialling method and select Auto from the drop down menu.
Set Idle Time to 86400 seconds. Click Submit.
Huawei HG523a / Huawei HG533
Select Basic then WAN, set Connection Trigger to auto, and Idle time out to 0 Seconds.
Click Submit to save.
Choose SETUP from the top menu, then ADSL Setup from the left hand menu.
Scroll down to the section Internet Connection Type.
Set Idle Time Out to 0. Then click Save Settings.
Choose SETUP from the top menu, then Internet Setup from the left hand menu.
Scroll down to WAN section.
Set Connect mode to always on and idle time to 0
The IP address to access Netgear routers is 192.168.0.1
The default username is admin, and the default password is password.
Choose Setup from the top menu, then ADSL Setup from the left hand menu.
Set Idle time out to 0 then click Apply.If you have a different model of router than those listed here, the idle time settings will usually be found under the WAN section in most routers. Look for the option Connection Trigger or Idle Time out and these can be set accordingly.
For example, Belkin routers may have an option to Disconnect after X minutes of inactivity. Billion routers have an option under Wan section to ‘enable keep alive’.
This has been asked multiple times already, and each time one of our Community members has pointed someone in the right direction of a guide on the internet, and some guides, understandably are better than others!
In order to save you some time we thought we would post a 'how to' for those that are interested.
In the following scenarios the primary router will be the one that is connected to the phone line and the slave will be the router used to extend the network (The slave is more correctly termed a wireless access point when used in this way).
There are 2 ways of gaining extra wireless coverage utilising 2 routers. (And if you want to plug in a device to one of the slave routers LAN ports this will work too, so it can also make the slave a hub for a smart TV, YouView box, Blueray player etc to plug into and connect to your home network as well as extend the wireless network) METHOD 1
This should only be used as a last resort as it will severely restrict wireless performance, the second method is preferable and is the one to use unless you have no other choice!
This first method uses the slave router as a 'wireless repeater' and you need at least one of your routers to be capable of being used in this way, a great many home routers won't connect like this, and that includes all of the talk talk supplied ones.
WDS (Wireless Distribution System)
This is the easiset wireless repeater to set up:
You activate the WDS function on both routers if they have it and they will find each other/pair themselves up and start working!
If you only have one router with a wireless repeater capability then this will be used as the slave:
You will need to log in to that routers internal pages
Activate the repeater function
Insert the wireless name/password to connect to the primary router wirelessly just like setting up any other wireless device like a laptop etc. again once this has been done they should 'just work'
This does require a few more steps, but you will get superior performance to any other method as it using all of the available wireless bandwidth for your devices and there is no signal degradation issues between routers. Our slave will be connected to the primary via an ethernet connection, whether this is a physical cable* or you want to use 'home plugs' makes no difference, the principles are the same.
Our primary router
This will issue all IP's on our network and it typically will have its own IP of 192.168.1.1 and its subnet mask will be 255.255.255.0 its own default gateway will be your outward facing IP and this is automatically inserted by the router itself.
We are going to use the next available IP - 192.168.1.2 - to give our slave router (we will set this as a static IP in the primary routers config pages), so on the primary router we are then also going to alter the DHCP pool (the IP addresses the router will issue devices when they want to connect) so that this IP is not issued to anything else. So in this example the primary routers DHCP pool will now be changed to 192.168.1.3 - 192.168.1.254
This will to be given an IP on the subnet of the first router (not strictly required we could use any IP range for the slave, but we are going for a simple solution here )
So in our example above I would give the slave router an IP of 192.168.1.2 (this will often be called 'own IP' in the routers interface) and I need to turn off DHCP on this slave, remember we do not want it to issue IP's, we only want to use its wireless function or its LAN ports to connect to my primary router, and then out to the internet!
You will need to connect to the slave via ethernet cable to configure it, and very often this set up will only work using LAN port 1 on many home routers...
You should also turn off any firewall functions on the slave and UPnP too for good measure, as the primary router will now do all of these functions. For subnet on the slave we should still use 255.255.255.0 and we should give the slave router a 'default gateway' IP of the primary router (our gateway to the internet), so in our example 192.168.1.1
Both routers will use the same wireless network name and password, when it comes to wireless channels some guides will say to use the same channels for 'roaming', but this can easily confuse your wireless devices as the slave wireless will then compete with the primary wireless, I prefer to use a different wireless channel on each access point, primary and slave, to prevent this.
And when you configure your routers you will need to connect them one at a time to your computer using a LAN cable and do all the changes before connecting everything together on your home network
Before you setup email, it is important to understand some of the different ways you can access it.
· The most common method is to access your email via ‘webmail’. This is where you can view your email through an internet portal directly from the TalkTalk website. Webmail can be accessed from any internet connection, for example, from a friend’s house or when travelling.
To access webmail, simply go to http://www.talktalk.co.uk/mail
· The other access options are POP3 and IMAP. These are from an email ‘client’ or program on your PC, Tablet or Smart Phone. POP3 is the more common option, however you should note, that when using POP3 access, emails will be downloaded directly from our mail server to your device. You can set an option to leave a copy of emails on our server, but if you do not do this, then the emails are your responsibility. If you delete these mails from your device, then they are gone forever and cannot be retrieved.
· IMAP is the preferred option and will connect to our mail server to manage the emails, folders and content directly on the server. This will give you access without downloading each email to your device.
To set up email…
You will always need four pieces of information:
· Your Email Address
· Your Email Password
· Your Incoming Email Server (usually mail.talktalk.net)
· Your Outgoing Email Server. (Usually smtp.talktalk.net)
You should make a note of these before you begin.
The following instructions will show you how to set up a TalkTalk email address, however if you are using one of the legacy email addresses, for example, @Tiscali.co.uk or @Lineone.co.uk, then you can find a full list of email server settings for your email address at our online help article : http://help2.talktalk.co.uk/email-settings-imap-pop3
Setting Up Windows Live Mail
Other email clients will have similar setup options, and as long as you have the four pieces of information mentioned above, then you should have no problems.
1) Windows Live mail, select Accounts them click the Email option
2) Fill in your account details
Add your email address, your email password and in the ‘Display Name’, how you would like your name to appear on emails you send. For example, Fred Bloggs or Mr F Bloggs etc.
3) Fill in your mail server addresses and email username.
For the server ‘type’ select IMAP. For the server address enter mail.talktalk.net with port 143.
Authenticate Using – make sure this says Clear Text.
Logon User Name - This will be your full email address.
Outgoing server – This should be smtp.talktalk.net Port should be set to 25.
If you wish to send email when travelling or from another network, such as from a Smart Phone etc, then outgoing port number should be set to 587 and select the option ‘Requires Authentication’. TalkTalk mail servers do not use SSL so this option should not be selected.
4) Click ‘Next’ then click ‘Finish’
That’s it. Your email address is added and ready to use.
5) Click ‘Send/Receive’ or press F5 on your keyboard and email will download to your inbox.
Set up guides for other email clients can be found at our online help section: https://help2.talktalk.co.uk/guided-assist/setting-email-my-computer
There are also guides for Smart Phone or Tablets : https://help2.talktalk.co.uk/guided-assist/setting-email-my-smartphonetablet
First you need to activate Last caller Barring within My Account
To block the last number to call you:
1. After the number you want to block has called you, dial
2. Confirm this by dialling
The last number to call you will now be blocked.
To enter a specific number you’d like blocked:
2. When prompted to manage your list of barred numbers enter your PIN (default is)
3. Select ‘Review your barred numbers list and edit it’
4. Now follow the instructions on the phone.
The number(s) you’ve entered will now be blocked from calling you.
You can also change your Last Caller Barring PIN using your phone. To do this:
2. Immediately enter your PIN (default is
3. Select ‘Change your PIN’
4. Now follow the instructions on the phone.
More of us are playing online games these days, and we're always looking for that little something to give us the edge over the ‘enemy’. Whilst it doesn’t use much data it can often be lost amongst high data applications such as video streaming.
For the best gaming experience you should, where possible have the console connected direct to the router with an Ethernet cable. If you currently connect via wireless, you may consider the use of powerline adapters that may give a better connection than wireless, I would suggest you check out Improving Wireless Performance over on the talktalk help site.
Improving gaming performance
Its suggested that you reserve an IP address for the Xbox or Playstation, and add this address to the routers DMZ. This will put the game console outside of the routers firewall, game consoles dont need this and it willhelp to reduce NAT issues etc. Before you reserve an IP address for your console, you will need to know the MAC address of the console.
Finding your XBOX 360's MAC address
From the home screen, scroll along to Settings, then highlight System and press Select (A)
Select Network Settings, and press Select (A)
Choose Wired or Wireless depending on your type of connection, and press Select (A)
Highlight Configure Network and press Select (A)
Highlight the IP settings section and press (A)
Highlight Advanced settings and press Select (A)
Under advanced settings, select Host Name, and write down the MAC address.
Note: Your MAC address will look something like ( 00-10-A5-59-D5-E3 )
Finding your XBOX ONE's MAC address
From the home screen choose Settings
Next, select Network then Advanced Settings
Select IP Settings, you will see a Wired and a Wireless MAC address . Write down the MAC address.
Finding your PS3's MAC address
From the PS3 Home menu, select System Settings
Select System Information, this will display the MAC address of your PS3
Finding your PS4's MAC address
From the Home menu, select Settings
Scroll down and select System and then select System Information
The Wired (Lan Cable) Mac address and Wireless (Wi-Fi) MAC address will be displayed. Note the MAC address for your connection type.
Reserve IP address for your console
First, you will need to log into your router from your PC or laptop:
Open a web browser
Enter 192.168.1.1 in the address bar.
When prompted for a username/password use: username = admin password = admin NOTE: If you have one of the newer talktalk routers the password will be different and can be found on the information label on the rear of the router
Select the Advanced option, and ok to the warning prompt about "for advanced users"
Scroll down to the router you're currently using for next steps.
Select BASIC then select LAN from the menu.
Select the DHCP tab, and at the bottom of the screen you will see IP Address reserve. Here you can select NEW and enter your device MAC address and select an IP address to reserve , something like 192.168.1.100
To add the address to the routers DMZ, select ADVANCED then NAT from the menu. Select the DMZ tab and enter the IP address you have reserved as the Host address, then click Submit.
HG635 Super Router
Select Home Network from the main menu, then select LAN Interface.
Scroll down to DHCP Reservation and select Create new static IP address
You may see the MAC address already listed, if not select Add device
Check ‘Enable this rule’ and then choose the IP address to reserve. When done, click Save.
To add this address to DMZ, select Internet from the main menu, then select Firewall. Scroll down to DMZ. Select your device from the Host Address drop down box. Check Enable DMZ and click Save.
Select SETUP from the top menu, then LAN Setup from the side menu
Scroll down to DHCP TABLE and select your device
Choose the IP address to reserve, and then set the Status to Static. Click Save Settings when done.
To add this address to the router DMZ, select ADVANCED from the top menu, then Firewall & DMZ from the side menu. Under DMZ settings, check enable DMZ, add the IP address or choose the device, then click Apply Settings.
Select SETUP from the top menu, then LAN Setup from the side menu
Scroll down to DHCP TABLE and select your device
Choose the IP address to reserve, and then set the Status to Static. Click Save Settings when done
To add this address to the router DMZ
Select ADVANCED from the top menu
Then DMZ (Exposed Host) from the side menu
Enable the DMZ option, enter your IP address. Click Add/Apply when done.
You may have a different model of router, or indeed, have purchased your own router. To reserve an IP address for a device, this option is usually listed under the DHCP settings, and these are usually found under LAN settings. DMZ options are usually listed under the firewall options.
If you have any problems, ask our community. There will be lots of help, and always someone waiting to point you in the right direction.
Determining the correct MTU Setting
A common cause of slow/hanging web pages, and/or poor streaming, can be due to an incorrectly set MTU (Maximum Transmission Unit).
Pieces of information or packets are sent to and from your computer grouped together. The size of this grouped packet of information is referred to as the MTU. For a more efficient connection, you can manually determine the maximum size of these packets before they fragment or break up. Most common MTU settings to try are:
1432 (This is the usual recommended MTU for Talk Talk but may not work for all)
You can try these values, or alternatively you can diagnose the exact figure yourself as below.
Please note that for Super Powered Fibre connections/routers, the correct MTU setting is 1500, and should not need to be changed.
How to determine your Optimum MTU
- Log into the router and set MTU to 1500 (just for testing purposes)
On your computer, open a command prompt. To do this, either click ‘Start’ and select Run (Windows 2000/XP/Vista/7) or press the Windows Keyand ‘R’. (All windows versions).
In the run box, type CMD and click OK or press enter. This will launch the command prompt.
In the cmd window type:ping -f -l 1472 www.google.co.uk (the l is a lower case L, and note there are spaces after ping, f, l, and 1472) You may get output that says something like "packet needs to fragment but DF set", or 100% packet loss, or “request timed out”. If you do, then type that command again, reducing the value of 1472 by small increments ie. 10, until you find the largest number which works with no lost packets. Then just add 28 to this number to set as MTU in your router settings. EG: max value with no packet loss = 1464, add 28 = optimum MTU of 1492.
To change the MTU value in your computer
Although you may have now entered the right MTU setting in the router, you may need to adjust the MTU in your computer system, as this may still be showing a default MTU which is different from your router MTU.
There are a couple of applications that can be downloaded to do this for you via an easy to use interface:
- One is Dr. TCP, but this does not work for Vista/Win 7/8, so here is a link to another application which will work for all versions of windows : http://www.speedguide.net/downloads.php
If you are comfortable with using the windows command prompt, you can do this yourself manually as follows:
- You will need to open a command prompt with administrator privileges. To do this (Win 7 and below) Click start, then type ‘cmd’ in the search box. The CMD.exe program will be shown in the program list. Right click on the program and select ‘Run as administrator’.
Windows 8, simply press the Windows key & X and in the pop up menu, select Command Prompt (Admin)
In the command window, type: ipconfig/all and press enter.
Make a note of the exact names of the network devices. They are the words directly after “adapter". Eg: “Local Area Connection" or "Wireless Network Connection".
Then use the following command to set the MTU value:
netsh interface ipv4 set subinterface "Network Connection" mtu=xxxx store=persistent
replace "Network Connection" with the name of the network device you made a note of above, and replacing xxxx with the new MTU value. More details on how to do this here: www.kitz.co.uk/adsl/vistaMTU.htm If you find that you are getting the “element not found message” when following above instructions, try the below procedure.
Rather than use the name of the interface, use its numerical ID. To get that ID, enter the following at a command prompt: netsh interface ipv4 show interfaces
Once you know the ID for the interface you want to tweak the MTU, use that rather than the description: netsh interface ipv4 set subinterface “X ″ mtu=1432 store=persistent (where 'x' is the ID of the interface)
Above is using MTU 1432, but of course, this needs to be same number as the MTU setting in your router. If working with the CMD prompt is a little daunting, then community member Fred_Sheehan has kindly provided some very helpful 'easy fix' configuration batch files for Vista and Win7 for the most common MTU values (see below links). These have been tested and are ok. Please note any fixes are at your own risk.
1392 MTU: http://www.4shared.com/file/xMmYRb0v/1392_MTU_Win7 _Vista_TcpIp_patc.html 1400 MTU: http://www.4shared.com/file/Y3ogpc5E/1400_MTU_Win7 _Vista_TcpIp_patc.html 1432 MTU (Talk Talk recommended default): http://www.4shared.com/file/ozswihnT/1432_MTU_Win7 _Vista_TcpIp_patc.html 1492 MTU (Optimise Mobile Broadband USB Sticks): http://www.4shared.com/file/3k4UKmde/1492_MTU_Win7 _V ista_TcpIp_patc.html 1500 MTU (Standard PC setting, best for LAN's or for Talk Talk's new fibre product): http://www.4shared.com/file/BNK1R701/1500_MTU_Win7 _Vista_TcpIp_patc.html
Improving Wireless Performance
There are actually two parts to your connection. The signal from the exchange to your house, and then the ‘wireless’ signal from your router to your device.
When your wireless ‘drops’ take a look at your router…
Is the ADSL (DSL) light off or flashing? If it is, then you may have an issue with a dropping broadband connection rather than a wireless issue
If you have no wireless signal, is the wireless light ‘on’? Some routers have a button at the side or back that can turn wireless on or off. Sometimes the simplest solution can be a button press. You can see the wireless or WLAN light is illuminated on the router below :
If you are having problems with your wireless connection, then here are a few tips to help improve the signal.
Finding the best position for your wireless router can sometimes be tricky. There are 2 things to consider:
The best place to receive the broadband signal
The best place for your wireless signal
It is usually recommended that you connect your router to your ‘Master’ phone socket. This will often give the best performance especially if you have a long line back to your local exchange.
If you have super powered fibre broadband:
Then your router must be connected to the main fibre socket
If you have standard ADSL broadband, and your speeds are fine:
Try another phone socket in your house
If you notice any drop in performance, we do recommend you move the router back to the main socket
To get a Strong Clear Wireless Signal…
You should place the router out in the open and off the floor, ideally near the centre of your property
You should also make sure it is a good distance away from walls, metal objects and electrical appliances. Placing your router on top of the TV for example, would not be a good idea.
Your router broadcasts wireless radio signals, and like all radio signals, it is possible to pick up interference. Microwave ovens, security cameras, Bluetooth devices, cordless phones, baby monitors and video senders all use a similar frequency and are all common causes of interference. You may not have such equipment in your house, but can you be sure what wireless equipment your neighbours are using?
It is worth checking that your router is broadcasting on a clear channel. Most routers will normally select this automatically, but it is always a good idea to set a channel manually to see if this helps. Channels 6, 9 or 11 are good options to try. To change the wireless channel for your router, see our help article https://help2.talktalk.co.uk/how-do-i-change-wireless-channel
If you have tried other wireless channels, and you are still seeing drops in your wireless signal, then try lowering the wireless mode. Wireless signals are broadcast over a range of standards that include 802.11 b/g/n or 802.11ac. To improve the stability, you can try changing the wireless broadcasting mode to use 802.11g as some older devices may not be equipped to receive signals at the latest wireless standard.
To change the wireless mode, log into your router by entering 192.168.1.1 in your internet browser program.
When asked for a username, this is ‘admin’ and the password is also ‘admin’.
When logged in, select the ‘Wireless’ option, and you should see the wireless mode. You can change this from b/g/n to just b/g. If you do not see the wireless mode, then you can select ‘Advanced’ to take you to the advanced router settings, and this option is usually listed under Wireless Settings or WLAN options.
Is the wireless signal poor or dropping on all your devices, or just one?
If you have multiple devices, PC’s, Smart phones, Tablets etc, could it be the device itself. For example, if your phone or tablet is connecting fine, and it is just the one PC or Laptop that is dropping the wireless connection, are the ‘drivers’ up to date for the wireless adapter? You may need to visit the manufacturer website to download the latest drivers for your operating system.
Another thing to consider, is the router itself.
Could this be faulty? If you have a friend or relative that use wireless devices in their home, and they have no problems, are you able to ask them to test your router to see if they can connect wirelessly with no issues?
If you have tried all the above, and you think there may be other factors affecting the wireless signal around your house, for example, you live in an older property with thick or stone walls, then you could look at possibly using a wireless range extender.
This is a relatively inexpensive device you can connect, usually somewhere between your wireless router, and the furthest device in the house. This will then boost the wireless signal to those parts of the house where wireless signals are weaker.
Alternatively you can look at devices such as powerline adapters that can route the broadband signal via the electrical wiring within your property.
These devices come in different speed options, so it is always a good idea to research these before you decide on a set to purchase. Try reading the customer reviews on websites such as Amazon, and this will help to give an idea of how these devices perform.
As more of us work from home, VPN is the preferred method to connect to a works network, and more issues are becoming evident.
There are 3 main types of VPN connection, and all require access details such as usernames or passwords. You may also require a security certificate, usually downloaded or provided by your server admin. If you are unsure of any of these details, you will have to check with local IT of the company you work for.
If VPN is set up correctly, but this is not working properly, then there are a few things to check.
MTU or Maximum Transmission Unit is the amount of data that is sent at a time. If unsure how to set or change your MTU settings, then see our article ‘Determine The Correct MTU Size’.
Generally, ADSL broadband is set to a recommended MTU of 1432, and Fibre will be set to 1500 but VPN likes smaller packets, usually 1430 or lower. You can try setting the router and your computer to use an MTU size of 1400 to see if this helps.
Router Passthrough Settings
Some newer routers may support ‘passthrough’ settings. You can check in your router to see if you have these settings, and if they are on.
The HG533 router, under Advanced then NAT then ALG tab, you can check that the relevant protocol is enabled (L2TP, IPSec or PPTP)
The HG635 Super Router, Under Internet then Port Forwarding, you will find the ALG settings. You can check the relevant option is checked.
D-link 3680 & 3780 do not currently support this feature.
NAT (Network Address Translation)
Routers use NAT to allow you to have different IP addresses on your home network. This can sometimes cause issues with VPN, so for older routers that do not support passthrough, you can turn NAT off to see if this helps.
D-link 3680 Under ADSL setup then Internet Connection Type, you have the option to enable or disable NAT
D-link 3780 Under Internet Setup, then under WAN, there will be an option to uncheck NAT
To use VPN, you may need to open specific ports. Below are some common ports, but if unsure check with your systems administrator to confirm the protocol and ports your company is using.
Some popular VPN protocols and ports :
IPSec port 500 & 4500
L2TP port 1701 & 500
PPTP port 1723 & 500
If unsure how to open ports, see our article : Set up port forwarding.
This covers some of the more common issues of VPN, if still having any issues with configuring VPN, ask our community. There are many experienced members that will be only too glad to help.
You're not normally allowed to have services on more than one set top box within your home, unless you pay an additional fee and in TalkTalk's case its not currently possible however its a restriction that affects all providers.
Some providers will offer a multiroom service, you can usually pay an increased monthly fee for a second set top box. There are however other alternatives that you can use to receive the television signal in another room.
This option is using a device known as a Video Sender. These have been on the market for many years and rely on a wireless signal to transmit to a receiver connected to your second TV.
Most video senders allow you to transmit the remote control signal from another room, back to the set top box so that you can change channel or view the guide information etc.
These devices have a wide price range, and can operate across the main wireless frequencies. Before deciding to purchase these devices, I would always suggest you read through the customer reviews for each model and see what other customers are saying about their performance.
You can convert the HDMI signal to an Ethernet signal, this will allow you to transmit the TV signal either wired, if you have LAN cables in place between rooms, or by using Powerline adapters. Some powerline adapters have 2 ethernet sockets and can carry the network signal from your router & TV signal from the HDMI converter.
You may require a HDMI splitter to allow you to feed the TV signal from your set top box to your main TV and to the converter at the same time. The downside of these converters, is that it will not allow you to transmit the remote control signal back to the set top box, and you will not be able to change channel while in another room.
Strictly speaking any PC, laptop, phone, or tablet does not connect via a Wireless LAN (WLAN) connection to a router. They connect instead to something called a Wireless Access Point (AP). In fact the home broadband router is made up of several parts:-
ADSL or VDSL (fibre) modem. This connects the router to the ADSL or VDSL line coming in to your property. Note: not all fibre routers have an inbuilt VDSL modem. The only TalkTalk router that does currently have one, is the HG635 Super Router.
The actual router. The purpose of this is to route IP packets between the local network & any other network - normally the internet (or any other network that the router knows about).
The LAN (Local Area Network) – this provides a wired connection to devices.
The Wireless AP – this allows connections from wireless devices.
Each device you want to connect to any form of LAN (Local Area Network), be it wired, or wireless requires a network adapter. This handles all of the TCP/IP communication with the router. Most of these are built into laptops, phones & tablets etc in the form of a wireless network adapter, with laptops normally also having an Ethernet (wired) adapter. Most desktop PCs will have an Ethernet adapter built into the motherboard, but they normally require an additional wireless adapter, if this type of connection is to be used. This can either be a USB wireless network adapter, or a card inserted into the PC's motherboard (usually in a PCI slot).
Open Systems Interconnect
In addition to this, once any connection is established, the network adapter must have a “TCP/IP stack” that conforms to something called the “OSI 7 layer model”, OSI stands for “Open Systems Interconnect”. This ensures that all of the TCP or UDP communications that run over this IP link will be able to be understood by both the device & AP. If this was not enforced, then if you had a router made by company A, you would not be able to use a wireless, or wired device whose network adapter was made by company B.
A router can contain a number of RJ45 ports often marked up as LAN1, LAN2 etc. There are several variants of Ethernet wired connections. These may run at one, or all of the speeds listed below (depending on the specification of the home broadband router):-
Ethernet - 10Mbps at half-duplex (one direction at a time)
FastEthernet – 100Mbps at full-duplex (transmit & receive data and the same time)
GigabitEthernet – 1Gbps (1000Mbps) at full-duplex.
All IP networking relies on equipment conforming to certain standards so as any vendors kit will work with any other vendor, so long as they both conform to the same standard. The standards for wireless networking is defined by the IEEE - the Institute of Electrical and Electronics Engineers.
The main IEEE specification for Wireless networking is called :-
There is a suffix letter, which denotes how fast (amongst other things) that this wireless connection can run. However, please note that most wireless communications carry a lot of overheads, so you would never get this sort of throughput of data, it will always be less. Most of these run in the 2.4GHz frequency band. Some newer routers and network adapters will also run at 5GHz (normally called dual band routers or network adapters).
The 2.4Ghz frequency range is shared with other types of RF (Radio Frequency) devices such as microwaves ovens, cordless phones, door bells, car remote central locking, wireless keyboards & mice etc. This band is subject to interference from other 802.11 APs using the same channel, plus background interference from the above mentioned devices.
The 5GHz band is much better for 802.11n & above, because it is a much less prone to interference, as it is not in the same band as these other common household devices and the signal will also travel further.
Dual band routers effectively consist of two APs, one for each band. To use the 5GHz band, the router plus any devices that you want to connect to it must both be dual band. If you have some devices that only support 2.4GHz, they can still connect to the 2.4GHz AP.
These specifications are often referred to in manufacturer terms as the “Wireless Mode” and can include 802.11n, the full list is:-
802.11b – 11Mbps at 2.4GHz.
802.11g - 54Mbps at 2.4GHz.
802.11n - up to 300Mbps at 2.4 and 5GHz (if dual band). The 300Mbps requires the 802.11n bandwidth option is set to 40MHz on both the AP & connected device, or it will only run at 150MBs.
802.11ac -500Mbps. This is very new & although some routers support, currently most devices do not.
Most 802.11n routers will by default allow connections from all modes (b/g/n), this gives the most compatibility. However, the wireless mode that is used will be determined by the slowest device. If say 3 devices are capable of running at 802.11n & one can only run at 802.11g, then they will all run at 802.11g.
A wireless network if not encrypted is potentially open to any hacker to read the data being transmitted, or received. Therefore it must always be encrypted, this encryption process is one of the things that contribute to the overheads on such a connection, as mentioned earlier.
There are various types of security protocol (WEP, WPA & WPA2) that the connection may, or may not be able to run (the same type must be supported on both ends of the wireless link), the earlier ones are now thought to be quick easy to crack & should never be used.
On top of the security protocol, WPA & WPA2 run encryption algorithms (such as AES) to encrypt your data. The types you may see on a home wireless network are (going from the least to the most secure):-
Open Network (no security at all)
WPA + TKIP
WPA + TKIP/AES (TKIP is there as a fallback method)
WPA + AES
WPA2 + AES – this is the only one that should currently be used & is default on most TalkTalk routers
The only one you should use currently is WPA2. WPA2 has two variants:-
WPA2 Personal - Wi-Fi Protected Access II Personal.
WPA2 Enterprise - Wi-Fi Protected Access II Enterprise
The enterprise version of this needs access to something called a RADIUS server to work. It is not supported on the vast majority of domestic broadband routers. The personal variant, used along with the AES encryption algorithm provides the highest protection level currently available in a home network.
Each network needs to use a channel (a channel is actually just a smaller frequency band, typically 20MHz wide). On the AP, if too many nearby networks are trying to use the same channel, then they will interfere with each other. This will reduce the speed & cause drop outs of the signal etc.
Most routers advertise that they support 11 different channels, but in reality you can only use channels:-
1, 6 & 11
This is due to the way 802.11n can bond two channels together (40MHz) for its increased bandwidth required to get 300Mbps. For more details see this webpage.
Connecting to a wireless network
Once the router has been configured, this normally a simple task of selecting the network name you want to connect to & supplying the correct pass phrase (password).
The network name is actually called the SSID (Service Set Identifier). By default on a TalkTalk router this is set to “TALKTALK-xxxxxx” where the last six characters will vary depending on your router. This information will have been provided to you, along with the default password. It is possible to prevent your router from advertising its SSID. This was thought to be a security measure, but it can still be found out by a potential hacker, so there is little point in doing this. Some Apple devices do not like the hyphen, or other special characters in the SSID or password. So if you are having connection problems with these, try changing the SSID & password to only contain upper & lower case letters, plus numbers.
Dual Band routers
These have two APs built into them, one operating at 2.4GHz and the other at 5GHz. They are often configured to use the same SSID. This can make it very difficult to tell which band you have connected to. It is therefore best to configure each band to have a different SSIDs. These two APs are totally independent from each other, so you could for example have devices connected at 2.4GHz at 802.11g and all devices in the 5GHz band running 802.11n. Not all WLAN network adapters are dual band.
MAC Address Filtering
This is a way to prevent any wireless device except those approved by yourself from accessing your WLAN. This is not totally foolproof, but is a very good basic security measure.
Every network adapter has a hardware address burnt into it. This is called a MAC (Media Access Control) address. On the router you create a list of approved MAC addresses and all others will be rejected when they try to connect.
The procedure to configure this is too lengthy to include here, please contact me if you want a copy of my documentation on this.
There are numerous options available for the 802.11n wireless mode, the most commonly supported on most routers being:-
.n bandwidth (sometimes called “Channel Bonding”)
802.11n bandwidth - this will allow the network adapter of the attached device to work at speeds of either 150Mbps, or 300Mbps. It can achieve this increased speed by bonding a second channel, with each channel being 20MHz wide, this option when enabled is often called 40MHz. However, if there is interference on the wireless channel, you will never get the 300Mbps advertised speed. To achieve this speed will also depend on how many antennas your network adapter has. When this is enabled & you use an analyser such as “inSSIDer Home”, you might see that despite configuring the router to use say channel 1, it is actually using channels 1 & 5.
However, some manufacturer's network adapters do not work well, or not at all with this option enabled (notably Apple products – although hopefully they will sort this). So you can try disabling this option & if the device will then connect, no other device on your network can use this increased speed.
Guard interval – this is the space between symbols (characters) as they are being transmitted. Shorter intervals can increase throughput, but can lead to interference between characters. The guard interval is there to eliminate inter-character interference, this happens when echos (reflections) from one symbol interfere with another. Adding time between symbol transmissions allows these echos to settle out before the next symbol is transmitted. In normal 802.11 operation, the guard interval is 800 ns.
With 802.11n, shorter guard intervals are possible. The short guard interval time is 400ns, or half of what it used to be. Shorter wait time (guard interval) between symbols increases throughput. However, if it's too short, the amount of ISI will increase, and throughput will decrease. On the other hand, if the guard interval is too long, there is increased overhead due to the additional idle time. Using Short Guard Interval increases the data rate by roughly 10-11%.
My other technical blogs include:-
IP Addressing & Ports
D-Link routers – getting statistics
Connect to the router
In your browser go to:- http://192.168.1.1 Enter a username & password of "admin" without the quotes (unless it has been changed from default):-
Click on the "Status" on the top:-
Then click on the “Statistics” tab on the left hand side:-
This will give you the statistics page:-
Take a screenshot When displaying this page, either press the <PrtSc> key to copy to the clipboard and then paste it into Microsoft Paint, or similar image editing software. Then save it as a .png, or .jpg. If using Windows 7 or later there is a much better way to copy this to the clipboard. With the statistics screen as the active window, launch the application “Snipping Tool”:-
Then move the cross hairs to the top left of just the part of the area you are interested in (e.g. ADSL Statistics) and drag the mouse to the bottom right and release the mouse. Then when it loads up in the Snipping Tool click on the “Save” button. If you make a mess of it, click the “Cancel” button in the Snipping Tool and then click the “New” button to have another go.
Include in Community forum To include in the Community forum, go to the Attachments section & click “Choose file”:-
Browse to where you have saved the .png or .jpg file. Once you have completed your post message, clicking the “Post” button will take longer than normal to process, because your attachment is also being uploaded.
You may want to set a separate wireless network from the same router, for friend to use when they come round, setting this up is really easy.
Let’s get started:
First, log into the router. Open a web browser, and type 192.168.1.1
When prompted for the login details, username / password is admin.
Click Advanced, and OK to the prompt ‘for advanced users only’.
Under Basic, then WLAN, locate SSID index. Select the next available index, usually 2, then create a new network name (SSID) and a new wireless password (pre shared key). You can create up to 4 wireless networks.
HG635 Super Router
The Super Router does not have an option to create multiple wireless networks, however as this is a dual band router, you can set a different SSID for the two frequency bands. Select ‘Customise my Wireless Network’ from the router home screen.
Select ADVANCED then Advanced Wireless from the side menu. Check ‘Enable Wireless Guest Network’ Enter the required configuration details and click Apply.
Select AVANCED from the top menu. Next, hover your mouse over Advanced Wireless and you will see 3 options.
Select Multiple WLAN SSIDs and you can then add more wireless networks to the router.
Once created your friends can connect to your ‘separate’ wireless network when they arrive.
Step 1 - Backup your mailbox
Before you start changing your settings, it's really important that you create a backup of your mailbox. Changing your settings from POP3 to IMAP can cause your emails to be deleted, so you should always save a copy of your existing mailbox to avoid losing anything.
Before you start, you'll need to create a new folder to save your backup in. You should label this folder clearly and save it somewhere easy to find.
Open Outlook and select File.
From the dropdown menu, choose Open & Export, then Import/Export. A new window will open.
In the new window, select Export to a file so that it's highlighted in blue, then choose Next.
Now select Outlook Data File, and choose Next.
You'll need to select which folders to backup. We recommend that you make a copy of everything- so select your email address at the top of the list, making sure that the Include subfolders box is also ticked. When you're happy, choose Next.
On the next screen choose Browse, select the folder you created earlier, type in a file name and select OK.
Choose Finish and Outlook will export your mailbox to a file.
You'll now have a copy of your entire mailbox saved as a file on your computer.
Step 2 - Delete your POP account on every device
It's important that you delete your POP account on all of your devices, otherwise it will keep receiving your emails. To do this, follow the steps below.
Choose File, then Info.
Under the Account Information heading, choose the Account Settings box, then select Account Settings again from the dropdown menu.
Select your POP account so that it's highlighted in blue, and choose Remove.
To remove your account from your other devices, take a look at our device setup guides for email clients. Each article has a section on removing your account from that device.
Step 3 - Add your IMAP account on your computer
Now you've created your mailbox backup, it's time to re-add your old POP3 account using IMAP settings.
To add another email address, choose File in the upper left-hand corner of your screen.
Then select Add Account.
On the next page, click the circle next to Manual setup or additional server types and select Next.
You'll now see a screen asking you to choose your service, select POP or IMAP, then click Next.
Now you'll need to add your settings- it's important that you do this part carefully. To get the correct settings for your email address, go to our help page for email settings, choose your email address from the list, and then use the settings under the IMAP (recommended) table heading. You'll need to fill in the sections as shown below:
Email Address: Enter your email address
Account Type: Select IMAP from the drop down list.
Incoming mail server: Check our help article for the correct setting.
Outgoing mail server (SMPT): Check our help article for the correct setting.
Username: Enter your email address again.
Password: Enter your email password.
Remember password: Make sure this box is ticked.
When you've entered all of the above details, click More Settings.
A new window will pop up. On the row of tabs, select Outgoing Server.
Tick the box next to My outgoing server (SMTP) requires authentication.
Click the circle next to Use same settings as my incoming mail server.
Now go back to the row of tabs, and select Advanced and enter the details as described below:
Incoming server (IMAP): Check our help article for the correct setting.
Set Use the following type of encrypted connection as None.
Outgoing server (SMTP): Check our help article for the correct setting.
Set Use the following type of encrypted connection as None.
When you have entered all of these details, click OK and the window will close.
Now you're back on the Add Account screen, click Next.
Outlook will now test your account settings to make sure all the information is correct. If you encounter a problem, it may be a good idea to carefully repeat the steps above and try again.
Once the test is successfully complete, click Close.
Your IMAP account is now set up.
Step 4 - Restore your mailbox
Now that you've setup your IMAP account, you can restore your old mailbox back into Outlook. Just follow the steps below.
The first step is to open Outlook.
Then choose File, and Open and Export from the dropdown menu.
Now select Import/Export, and a new window will open.
In this new window, choose Import from another program or file, and select Next.
Choose Outlook Data File so that it's highlighted in blue, then Next.
Select Browse, and find your backup file. When you've done this, choose Next.
Finally, choose which folder you'd like to restore your data into, and select Finish to complete.
Your mailbox will be restored back into your selected folder.
When a PC, laptop, phone, or tablet etc wants to access a website, the user via their web browser enters a website address (URL – Uniform Resource Locator), such as:-
Straight away there is a problem, the TCP/IP stack of any IPv4 networking device can only establish connections to IP addresses, not website addresses (URLs).
Well what is the IP address of Google then – answer - I don't know.
Quite a lot of the big websites use a “server farm” anyway, which means you would need to send the request to one of many IP addresses.
This is where DNS (Domain Name Service) comes in.
The device, without the user knowing, sends out a DNS query to try & find the IP address of the given URL. Another problem rears it's head – what is the IP address of the DNS server?
When the device connected to the Wi-Fi network, or wired connection to the router, it is allocated an IP address by the DHCP (automatic) process for itself to use, but actually it is given more than just that.
A typical DHCP "offer" to any client connected to the router would contain:- IP address : 192.168.1.x Subnet mask : 255.255.255.0 Default gateway : 192.168.1.1 DNS Server(s): 192.168.1.1
So now the device can send the DNS query to the DNS server (192.168.1.1 in this example). On receipt of the DNS query from your connected device, the DNS server (192.168.1.1 in this case) will respond with a “DNS Query Response”. Within that response is an “Answer” field that contains that website's IP address.
This device can now initiate a browser session to the IP address it has just been given and that web page should now be seen in the browser on the device.
This might seem complex, well welcome to the world of IP networking!
DNS Server operation in more detail
The top 13 root DNS servers (see DNS server hierarchy at the bottom of this document) plus the "zone" DNS servers normally have their DNS records synchronised. However, m ost home routers act as the DNS server for their clients, but in a mode called "Caching-only servers".
The DNS server within the router will build up a cache storage of URL/IP address pairs, as you visit numerous websites. Those it does not know, it will refer back to the DNS servers in your router's WAN configuration (e.g. TalkTalk, or openDNS etc), with what is known as a “recursive query”. These network DNS servers will then supply the router with the relevant IP address. The router's DNS server will update it's cache with this information & hand it out to the requesting device. If the network DNS servers do not know the IP address for the requested URL, they in turn will make recursive queries backup the hierarchical tree towards the master DNS server.
However, cache storage is temporary, based on time & how many entries it can hold. So every so often individual entries will time expire & be deleted from the cache. Each DNS entry has a Time To Live (TTL) field which could at anytime have a value of a few seconds, days or even weeks.
Once the TTL reaches 0, this entry is deleted from the cache. In addition to time these cache stores will have a maximum number of entries that they can hold. When it gets full it again will delete the entries with the shortest remaining TTL values.
Bear in mind that this is not a precise timestamp, so any delays in network propagation could lead to this TTL expiring a bit before or a bit later then maybe expected.
The specification covering the DNS operation is covered by RFCs 1034 & 1035.
PCs, other devices & DNS Caches
Any device connected to your router's network (wired or wireless) will have a DNS cache. How large this is may well vary between devices. They all work on the principle that any entry whose TTL decrements to 0 seconds, is deleted from the cache.
The server may well be able to hold more entries than the cache on a PC.
Consider this, there are two PCs connected to the same broadband router, which for simplicity are called A & B. The following sequence could easily happen.
B is currently turned off.
A wants to go to the BBC's website & it still has an entry for this website in its own DNS cache, with a TTL of 360 seconds. So no DNS query required:-
A's entry in its DNS cache times out & is deleted, In addition to this, the entry for the BBC in the router's DNS cache times out & is deleted.
B has just booted up & therefore has no entries in it's DNS cache.
B wants to do a Google search for the BBC. It does not have any entry for Google in its DNS cache, so it makes a DNS query to its DNS server (the router) for Google. This is in the DNS cache of the router and on receipt of the DNS response,
B updates its cache:-
B can now access Google.
B clicks on an entry in Google for the BBC's website, but there is no entry in its DNS cache for the BBC.
So it makes a DNS query back to its local DNS server (the router). However, the router has no entry for the BBC in its DNS cache either. So the router has to make a recursive DNS query back to the next layer up the DNS server tree hierarchy for the BBC:-
The DNS caches for the router & B are updated, showing the BBC entry with a TTL of 1 day.
Note that A's cache is not updated at all with the new information provided to B.
B is then able to visit the BBC website:-
A now wants to go back on the BBC website, but there is no entry in its DNS cache any more after it timed out a while ago. So it has to make a DNS query to its DNS server (the router):-
The DNS cache on A is now updated to include the entry for the BBC & is able to proceed to their website.
Note 1 : this DNS query was made approximately 1 minute 15 seconds after the DNS server in the router updated its cache from the DNS server tree hierarchy now including the BBC entry.
A updates its cache, but the TTL for the BBC has decremented to 23 hours 58 mins & 45 secs in the router's DNS cache, so this is the TTL value that was passed back to A in the DNS response.
Note 2 : the TTL value for the BBC in B's DNS cache now also shows 23 hours 58 mins & 45 secs as well. It is not synchronised to the DNS server, it has just decremented to this value as part of its normal aging process.
Note 3 : In all of the diagrams the cache entry for Google has remained with a TTL of 5 days. Strictly speaking this has also reduced its TTL as it ages, but as this is example only covers a few minutes in total, it has been left at 5 days to simplify this explanation.
Display DNS Cache on a Windows PC
To display the DNS cache on a Windows PC, go to a command prompt and enter the command:-
the result will look something like this (only a few entries are shown):-
www.bbc.co.uk ---------------------------------------- Record Name . . . . . : www.bbc.co.uk Record Type . . . . . : 5 Time To Live . . . . : 151 Data Length . . . . . : 4 Section . . . . . . . : Answer CNAME Record . . . . : www.bbc.net.uk
www.google.com ---------------------------------------- Record Name . . . . . : www.google.com Record Type . . . . . : 1 Time To Live . . . . : 218 Data Length . . . . . : 4 Section . . . . . . . : Answer A (Host) Record . . . : 18.104.22.168
The Time To Live field in each entry can be plainly seen in the example above.
Although the cache does not get flushed (except when the PC reboots), it can be manually flushed if it is required. To do this enter this command from the command prompt:-
The goal of an efficient DNS system, is to have as few DNS queries being made as possible. If an end user wants to access a certain website, it will resolve the URL to an IP address much more quickly, if it can get it from cache. If however, it does not have an entry in its cache, it makes a query to its local DNS server. It is quicker if that server can supply the information out of its cache, rather than making a recursive DNS query up the tree to its next DNS server etc.
This is why it is important that the DNS server address handed out to a device on connection to a network from its DHCP server, must be the local DNS server. Not one such as the TalkTalk, or openDNS etc. Try pinging your router and then the network DNS server. You will probably find that the router can be contacted in under 1ms, where the network DNS servers might be about 30-35ms away. That might not sound a lot, but every visit to a webpage via a URL, requires a DNS look up, so any saving improves performance.
An example from the DHCP offer, shows the DNS server address as 192.168.1.1:-
IP address : 192.168.1.x Subnet mask : 255.255.255.0 Default gateway : 192.168.1.1 DNS Server(s): 192.168.1.1
Otherwise the time taken to contact the network servers will be greater than that of a DNS server on the local subnet (local network) and thus increase the latency to display a website in the user's browser.
DNS Server hierarchy
To understand the DNS server hierarchy, have a look at:-
Then basically most companies like Cisco above link into this worldwide hierarchy somewhere, as do Google, openDNS, TalkTalk etc. All the router's DNS server is doing is linking into the Google, openDNS, TalkTalk DNS servers etc.
Google Content Cache
Sometimes when you check an Answer to a DNS Query, the IP address given does not seem right. An example of this is if you do a DNS request for youtube.com, and you do a "whois" on the returned IP address, that address is owned by your ISP, ot youtube. This is down to Google Global Cache (GGC) and is designed to improve the streaming of the video to the user.
An extract is shown below, for full details please see:-
"Google Global Cache (GGC) represents the final tier of Google’s content delivery platform, and is closest to users. With GGC, network operators and Internet Service Providers deploy a small number of Google servers inside their network to serve popular Google content, including YouTube. Google's traffic management system directs users to the node that will provide the best performance for the user."
DNS failure error
A DNS failure error can be misleading. Often the problem is that there is no internet connection rather than a specific DNS issue. Your browser requests a webpage and queries the DNS server, but because there is no internet connection, the browser can't contact the DNS server and so gives a DNS error.
Glossary of terms
Domain Name Service
This uniquly identifies an end device PC, router etc).
The way that a device can determine if an IP address is on the same network as itself. Normally in a home network this is set to 255.255.255.0.
This is the device that knows how to get to all other IP networks that are not local yo your network. This is your broadband router & is typically 192.168.1.1.
DNS Server Address
The IP address of the local DNS server, this would normally be the router's IP address in a typical home broadband network (192.168.1.1).
Dynamic Host Configuration Protocol – a method of automatically assigning all devices that connect to a network, all of the relevant IP addressinformation.
A temporary storage area of website addresses (URLs) and IP address pairs. This applies to home routers & all devices connected to its local network.
Time To Live – a field in the DNS cache record that determines how long to retain this entry in the DNS cache
Other technical blogs
LAN & Wireless LAN (Wi-Fi)
IP Addressing & ports