Enabling vBulletin 4 Facebook Connect on some servers would cause extremely slow page loads. Usually 2-15 seconds was added to the page loads of logged in users. I spent a lot of time troubleshooting this problem. Searching Google revealed little to no help; some solutions I found were:
- IPV6 port is blocked by the firewall
- Disable Facebook Connect in the vBulletin admin
A quick check revealed the necessary IPV6 ports were open and I did not want to shut a vital (to my users) feature off.
TROUBLESHOOTING SLOW VBULLETIN 4 FACEBOOK CONNECT
To find this problem, simply looking through the server logs revealed the problem. The most telling was ./var/log/messages. Errors in the log looked like this:
Jul 31 08:33:58 nsdomain named[26284]: error (network unreachable) resolving 'star.c10r.facebook.com/AAAA/IN': 2a03:2880:fffe:b:face:b00c:0:99#53 Jul 31 08:33:58 nsdomain named[26284]: error (network unreachable) resolving 'star.c10r.facebook.com/A/IN': 2a03:2880:fffe:b:face:b00c:0:99#53 Jul 31 08:33:58 nsdomain named[26284]: error (network unreachable) resolving 'star.c10r.facebook.com/AAAA/IN': 2a03:2880:ffff:b:face:b00c:0:99#53 Jul 31 08:33:58 nsdomain named[26284]: error (network unreachable) resolving 'star.c10r.facebook.com/A/IN': 2a03:2880:ffff:b:face:b00c:0:99#53 Jul 31 12:42:50 nsdomain named[26284]: error (network unreachable) resolving 'star.c10r.facebook.com/A/IN': 2a03:2880:ffff:b:face:b00c:0:99#53 Jul 31 12:42:50 nsdomain named[26284]: error (network unreachable) resolving 'star.c10r.facebook.com/AAAA/IN': 2a03:2880:ffff:b:face:b00c:0:99#53
This doesn’t help either:
Jul 31 10:21:16 nsdomain named[26284]: error (network unreachable) resolving 'vbulletin.org/DS/IN': 2001:500:48::1#53 Jul 31 10:21:16 nsdomain named[26284]: error (network unreachable) resolving 'vbulletin.org/DS/IN': 2001:500:e::1#53 Jul 31 12:19:20 nsdomain named[26284]: error (network unreachable) resolving 'vbulletin.org/DS/IN': 2001:500:f::1#53 Jul 31 12:19:20 nsdomain named[26284]: error (network unreachable) resolving 'vbulletin.org/DS/IN': 2001:500:b::1#53 Jul 31 12:19:20 nsdomain named[26284]: error (network unreachable) resolving 'vbulletin.org/DS/IN': 2001:500:40::1#53
The messages log was filled with these.
Using “Tail -f /var/log/messages” in the shell and loading a logged-in vBulletin 4 with Facebook Connect enabled web page told me everything I needed to know. As soon as vBulletin’s “Facebook Connect” initialized on a page load, the errors above would appear in the log.
SOLUTION
Enable IPV6 on the server so IPV6 DNS lookup could be executed server side. Or alternatively completely disable IPV6 and only use IPV4 (This is not a long term solution as IPV6 will be mandatory in the near future). If your vBulletin 4 Facebook Connect enabled website is on shared hosting you will need to ask your host to do this for you; if they won’t, you may want to change hosts.
CONCLUSION
The server could not perform IPV6 DNS look ups. Yet it still tried IPV6 first before it used the fallback IPV4 alternative DNS. This resulted in the the extra 2-15 second load times for logged in users. Until IPV6 is more widely used, IPV4 is the norm. Server setups are enabling IPV6 and sending traffic through it by default. One day IPV6 will be the norm and that will be fine, but until then we have to put up with 2 IP standards and the consequences of our ever-evolving technology.
Lesson here: Watch your log files!
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