Thunderbird DNS lookup fails unless IPv6 disabled

[tdasch]

I use Thunderbird to access work email at outlook.office365.com. I've been getting consistent "Failed to connect to server ..." error notifications when trying to fetch IMAP mail. I have found two workarounds.

Thunderbird works if I disable IPv6 in Thunderbird (Preferences->Advanced->Config Editor...).

It also works if I change the nameserver records in /etc/resolv.conf to point to Sonic's name servers instead of the Pace gateway.

From a wireshark capture it looks like Thunderbird fires two DNS queries back to back. The first query requests A records, the second requests AAAA. The Pace seems to delay the first request and answer the second with IPv6 addresses. Thunderbird retries both queries and again receives a quick response to the AAAA query. About a second later I see two A record responses. But by that time, it seems, Thunderbird doesn't process these.

For what it's worth, I have not enabled IPv6 on my account. I'm using stock IPv4 connections. It just happens that IPv6 is enabled by default in the Thunderbird application.

I don't need a fix for this as I have a couple workarounds. But I'm reporting it as it seems the Pace response for the IPv4 lookup is quite slow. That may affect applications other than Thunderbird.

[bhaveshmital]

I had a similar problem and probably more to do with resolv.conf or my faulty router(my own not provided by sonic.net) where in the first entry in my resolv.conf would become 192.168*** and followed by sonic.net dns entries.This would come up especially when I resume my debian wheezy laptop.
I wrote a script to zap the local router DNS entry and so far no issues.

[adame]

I use Thunderbird to access work email at outlook.office365.com. I've been getting consistent "Failed to connect to server ..." error notifications when trying to fetch IMAP mail. I have found two workarounds.

Thunderbird works if I disable IPv6 in Thunderbird (Preferences->Advanced->Config Editor...).

It also works if I change the nameserver records in /etc/resolv.conf to point to Sonic's name servers instead of the Pace gateway.

From a wireshark capture it looks like Thunderbird fires two DNS queries back to back. The first query requests A records, the second requests AAAA. The Pace seems to delay the first request and answer the second with IPv6 addresses. Thunderbird retries both queries and again receives a quick response to the AAAA query. About a second later I see two A record responses. But by that time, it seems, Thunderbird doesn't process these.

For what it's worth, I have not enabled IPv6 on my account. I'm using stock IPv4 connections. It just happens that IPv6 is enabled by default in the Thunderbird application.

I don't need a fix for this as I have a couple workarounds. But I'm reporting it as it seems the Pace response for the IPv4 lookup is quite slow. That may affect applications other than Thunderbird.

Thank you for the in depth report. I was able to reproduce this, and we will ask Pace to address this on our next firmware release.

[dhwalker]

Is this still an outstanding issue? I just started using Sonic today, and I had this exact problem (and worked around it by disabling IPv6 in Thunderbird). Since it's an old issue, though, I wonder if I have the most recent firmware in my Pace gateway.

[adame]

Is this still an outstanding issue? I just started using Sonic today, and I had this exact problem (and worked around it by disabling IPv6 in Thunderbird). Since it's an old issue, though, I wonder if I have the most recent firmware in my Pace gateway.

This is still a production issue, but I am (as we speak! ) testing a fix Pace has supplied to fix slow IPv4 DNS queries. The new code so far appears to address the issue, and we hope to roll this out to customers soon.

[dhwalker]

The new code so far appears to address the issue, and we hope to roll this out to customers soon.

Thanks. By the way, I ran into the same problem with Firefox. The same workaround can be used.