topic DNS Server Issues (Caching) in Broadband

DNS Server Issues (Caching)

dkeen94 — Tue, 15 Feb 2022 09:18:32 GMT

It appears that the Talk Talk DNS servers are not updating for a domain that I manage which means that any of my users that are attempting to access the website via their Talk Talk home connection is unable to do so. If I query the domain via 79.79.79.79 or 79.79.79.80 the supplied DNS servers on my router I am unable to resolve the domain name. If I query the domain via any other DNS server (208.67.222.222, 8.8.8.8) for example the site loads without any issue.

It appears according to TT DNS servers the domain no longer exists which it does, it appears it is just not updating its DNS cache.

Re: DNS Server Issues (Caching)

Chris-TalkTalk — Tue, 15 Feb 2022 09:29:42 GMT

Hi dkeen94,

Is this just recently happened, has it been OK in the past?

Chris

Re: DNS Server Issues (Caching)

dkeen94 — Tue, 15 Feb 2022 09:38:46 GMT

Hi Chris,

Up until yesterday it had all been fine however the domain nameservers were changed yesterday (prior to 9am) as part of a migration across to another provider. We had no issues reported following the change until one user spotted that they couldn't load the website or other web links for the domain in question. It wasn't until I investigated it a bit (I am also a TT customer) that I found that TT DNS is now unable to resolve the domain at all but others are. Its almost like the TT authoritative servers have dropped the DNS zone from its cache and are not updating to see the new updated zone. In google chrome we get "ERR_NAME_NOT_RESOLVED", if trying to resolve the domain via nslookup on a computer we just get "public-dns-a.as9105.net can't find <domain>: Server failed". However every other DNS server is able to resolve the domain without any problems.

I was doing some reading into this and I found some posts that a couple of other users have created saying that the TT DNS servers cache records for a long time (4+ days).

Re: DNS Server Issues (Caching)

Chris-TalkTalk — Tue, 15 Feb 2022 10:24:53 GMT

OK thanks. We would generally just advise you to give it a bit longer for the DNS servers to update, if after a few days they still haven't updated then we can raise it to our Network team for investigation

Chris