DNS Issues

[csalmeida]

Hi,

I am a developer working with CWM Environmental and the team has reported they cannot see the new version of the site at cwmenvironmental.co.uk

Users at the office (with internet provided by BT)  either end up at the old IP address (old version of the site) or see a "page can't be reached" screen. Everywhere else the new site can be visited with no issues.

I have also issued a request for their IT department to look into reseting their router(s) but this didn't yield results unfortunately.

Initially, I thought this could be a DNS propagation issue but that has completed a while ago and since the issue didn't go away and since the site is accessible out of the office with other ISPs. Could be a cache that is stale on BTs side since users with other ISPs can visit the site?

If that can be the case, how can I contact the network team to look into the issue please? 
I am not a BT customer by the way I'm just trying to sort out an issue on behalf of a customer.

Thank you for your time, I hope to hear from you soon.

[Keith_Beddoe]

@csalmeida 

This is just a customer to customer help forum, everyone here, including myself, are just customers.

The only BT Employees are the forum moderators.

[csalmeida]

Thanks Keith, in that case is there a way for me as a non-customer to contact BT directly for this sort of issue?

Appreciate the help.

[Crimliar]

Someone would need to verify this, but I cannot see any DNS propagation issues with the site on IPv4, but from what I can see anyone on a pure IPv6 network is not going to the site at all - anywhere, not just from BT!

[gg30340]

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@Crimliar wrote:

Someone would need to verify this, but I cannot see any DNS propagation issues with the site on IPv4, but from what I can see anyone on a pure IPv6 network is not going to the site at all - anywhere, not just from BT!

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I can access the site no problem using IPv4. I don't have IPV6 only but suspect you may be correct.

[csalmeida]

@Crimliar thank you very much, I didn't think of this before and it might help.
I could enable IPv6 on the site and see if that fixes the issue.

Hosting support says:

After reviewing on our end, it appears that there is likely an issue with the route that traffic takes from your location to your Droplet. Could you share the following information to help us verify and troubleshoot this issue?
1. What is your public IP address? You can use http://whatismyip.akamai.com/ to find out if you're unsure. 
2. Who is your ISP? 
3. The MTR (with 'mtr -rwbzc100 x.x.x.x'), from yourself to the droplet. 
4. The MTR, in the opposite direction from the droplet to your public IP address from step 1. 

However, getting the team to go through this process and send the output might be challenging.

[Les-Gibson]

@csalmeida 

@Crimliar is correct, an IPv4 ping confirms that the site has a valid IPv4 address but an IPv6 ping fails miserably stating that the host could not be found.

(ping -6 cwmenvironmental.co.uk from a Windows console) without the brackets

[csalmeida]

Thank you @Crimliar and @Les-Gibson. 
Following your suggestion I've enabled IPv6, configured it and added AAAA records for the domain.

Do you see any changes on your side? Appreciate the help as this has been really challenging to debug on my side.

Ping output:

ping -6 cwmenvironmental.co.uk
PING cwmenvironmental.co.uk(2a03:b0c0:1:d0::35a:8001 (2a03:b0c0:1:d0::35a:8001)) 56 data bytes
64 bytes from 2a03:b0c0:1:d0::35a:8001 (2a03:b0c0:1:d0::35a:8001): icmp_seq=1 ttl=64 time=0.064 ms
64 bytes from 2a03:b0c0:1:d0::35a:8001 (2a03:b0c0:1:d0::35a:8001): icmp_seq=2 ttl=64 time=0.062 ms
^C
--- cwmenvironmental.co.uk ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1002ms
rtt min/avg/max/mdev = 0.062/0.063/0.064/0.001 ms

[licquorice]

Accessible via IPv4, not accessible via IPv6 using Google IPv6 DNS servers. BT use IPv4 DNS servers for IPv6 addresses. Haven't tried using IPv4 DNS to IPv6 address as just disabling IPv4 in network adapter to force IPv6 connection.

[csalmeida]

Gotcha, this is super helpful thank you.

This means perhaps it's not that the broadband IP is blocked on the hosting side (like BT support suggested) as I'm assuming you, @licquorice  and @gg30340 are BT customers and can access the site fine.

I wonder if this ends up being stable DNS cache at the router level and it needs to be cleared in order for the domain to resolve to the right IP. 😅