This topic

BT DNS not resolving certain addresses - e.g. www.aerobus.fr

durks — Thu, 14 May 2026 07:41:03 GMT

Using standard BT broadband at home, I am unable to resolve either of the domain names www.aerobus.fr or aerobus.fr - the DNS lookup just fails. But those are valid domain names and, if I try to resolve them via my mobile network provider, that works fine.

This implies a problem with BT's DNS servers.

Do other people here see the same failure?

[Mod edit - removed hyperlink to website]

Re: BT DNS not resolving certain addresses - e.g. www.aerobus.fr

gg30340 — Wed, 13 May 2026 17:22:53 GMT

The link work fine as does the domain name.

Re: BT DNS not resolving certain addresses - e.g. www.aerobus.fr

durks — Wed, 13 May 2026 17:29:31 GMT

Okay, thanks. I will investigate further to see if I find some local issue. It's definitely odd though - all other domain name resolution is working fine for me.

Re: BT DNS not resolving certain addresses - e.g. www.aerobus.fr

durks — Wed, 13 May 2026 23:01:49 GMT

I'm still puzzled by this - and I see the same problem on both Linux, and Windows.

Can you please tell me the IP addresses of the BT name servers you're using? Thanks.

For me, it's 81.139.56.100 (primary) and 81.139.57.100 (secondary).

Re: BT DNS not resolving certain addresses - e.g. www.aerobus.fr

gg30340 — Wed, 13 May 2026 23:08:49 GMT

They are the same as yours, 81.139.56.100 (primary) and 81.139.57.100 (secondary).

Re: BT DNS not resolving certain addresses - e.g. www.aerobus.fr

licquorice — Thu, 14 May 2026 07:08:06 GMT

@durks do you have any parental controls enabled? They are network level controls and will be OS agnostic.

Re: BT DNS not resolving certain addresses - e.g. www.aerobus.fr

durks — Thu, 14 May 2026 08:47:47 GMT

Thanks for the suggestion.

I have not (knowingly, anyway) applied any such controls.

Logged into my router (a Smart Hub 2) as admin, I see the following note in the 'Access control' panel:

"Access controls are now managed using the app."

Sigh ... so I have now installed the 'My Bt' app on my phone. In that app, the only option for access controls appears to be a 'Control wi-fi access for your devices' section, and there is nothing active in that section.

Am I missing an explicit 'Parental controls' setting?

(BTW the PC on which I am typing this - and on which I first noticed the name resolution problem - has a wired network connection.)

I will persist in trying to debug my problem with 'dig' and friends and, if/when I make progress, I will post back.

Thanks.

Re: BT DNS not resolving certain addresses - e.g. www.aerobus.fr

gg30340 — Thu, 14 May 2026 08:56:40 GMT

This may not help but you could try a factory reset on your BT hub. This will force an IP address change and restore all the settings on the hub.

This will at the least give you a " clean page" to be working from.

Re: BT DNS not resolving certain addresses - e.g. www.aerobus.fr

durks — Thu, 14 May 2026 22:13:54 GMT

FWIW, this is now looking like a routing problem to me: I don't think I have functional routes to the specific nameservers.

The exact details - which depend on external configurations - are very difficult to diagnose, however ...

Re: BT DNS not resolving certain addresses - e.g. www.aerobus.fr

durks — Sat, 16 May 2026 18:33:07 GMT

By now, I am pretty certain that the cause of the problem I noticed (essentially, by chance) is a downstream IP routing issue caused by a configuration error in peering arrangements between ecritel.com and other network providers. Whether or not other BT users notice the same problem will depend entirely on where they are located (it just depends on which particular routes any such users will be taking), and whether or not they are accessing related end services.

The full details are impossible for me to fully diagnose - but I would be interested to know whether or not anybody can suggest a suitable way to escalate the problem, in order to try to get it resolved.

Thanks.

Re: BT DNS not resolving certain addresses - e.g. www.aerobus.fr

bobpullen — Fri, 22 May 2026 20:12:11 GMT

@durks - can you get to bt.com?

I recall an odd occasion some time ago where BT's nameservers seemed to be refusing all connection attempts from my IP address. I resolved the issue by downing my router for a period of time so I was assigned a new WAN IP address.

FWIW, the domain name resolves fine for me: -

~$ dig www.aerobus.fr @81.139.56.100 ; <<>> DiG 9.18.49-1~deb12u1-Debian <<>> www.aerobus.fr @81.139.56.100 ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 1476 ;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 1 ;; OPT PSEUDOSECTION: ; EDNS: version: 0, flags:; udp: 1232 ;; QUESTION SECTION: ;www.aerobus.fr. IN A ;; ANSWER SECTION: www.aerobus.fr. 60 IN CNAME book.distribusion.com. book.distribusion.com. 60 IN A 34.160.19.16 ;; Query time: 104 msec ;; SERVER: 81.139.56.100#53(81.139.56.100) (UDP) ;; WHEN: Fri May 22 21:09:10 BST 2026 ;; MSG SIZE rcvd: 94

Re: BT DNS not resolving certain addresses - e.g. www.aerobus.fr

durks — Fri, 22 May 2026 21:49:38 GMT

Thanks for the reply.

And yes - I can definitely get to bt.com.

By now, I am quite certain that the problem I am described is being caused by an IP routing error far downstream from me. But the exact cause is impossible for me to diagnose - and I don't really know to whom I should escalate. I am pretty sure that the problem will be noticed fixed - in due course!

Re: BT DNS not resolving certain addresses - e.g. www.aerobus.fr

bobpullen — Sat, 23 May 2026 07:48:54 GMT

@durks - if the problem is routing to the domain's nameservers then am I correct to assume that using a non-BT DNS server has no bearing on things, i.e. that fails too?

I still maintain that it's worth you powering things off for a while so you're reassigned a new public IP to see if that helps.

If it's of any help, this is my route to the domain's nameservers over IPv6 and IPv4 (and as mentioned, I have no issues resolving the domain): -

> tracert ns-219.awsdns-27.com Tracing route to ns-219.awsdns-27.com [2600:9000:5300:db00::1] over a maximum of 30 hops: 1 <1 ms <1 ms <1 ms 2a00:23c6:d00b:8c01::1 2 1 ms 1 ms 1 ms 2a00:2302::1103:203:3c3 3 * * * Request timed out. 4 * 8 ms * 2a00:2302::1102:100:49 5 8 ms 8 ms 7 ms 2a00:2380:14::221 6 8 ms 8 ms 8 ms core5-hu0-3-0-26.faraday.ukcore.bt.net [2a00:2380:c::338] 7 9 ms 9 ms 9 ms 2a00:2000:2066::7c 8 14 ms 14 ms 14 ms t2c3-et-5-1-5.nl-ams2.gia.bt.net [2a00:2000:0:80c0::5a] 9 * * * Request timed out. 10 * * * Request timed out. 11 * * * Request timed out. 12 * * * Request timed out. 13 * * * Request timed out. 14 16 ms 16 ms 16 ms ns-219.awsdns-27.com [2600:9000:5300:db00::1] > tracert -4 ns-219.awsdns-27.com Tracing route to ns-219.awsdns-27.com [205.251.192.219] over a maximum of 30 hops: 1 <1 ms <1 ms <1 ms hub.home.arpa [192.168.1.254] 2 1 ms 1 ms 1 ms 172.16.17.177 3 * * * Request timed out. 4 8 ms 8 ms 8 ms 109.159.255.96 5 8 ms 8 ms 8 ms 109.159.250.147 6 10 ms 10 ms 10 ms core5-hu0-0-0-26.faraday.ukcore.bt.net [195.99.127.68] 7 7 ms 7 ms 8 ms 166-49-209-132.gia.bt.net [166.49.209.132] 8 14 ms 14 ms 15 ms t2c3-et-5-1-2.nl-ams2.gia.bt.net [166.49.208.217] 9 * * * Request timed out. 10 * * * Request timed out. 11 * * * Request timed out. 12 * * * Request timed out. 13 * * * Request timed out. 14 15 ms 15 ms 15 ms ns-219.awsdns-27.com [205.251.192.219]