For some reason, traceroute to hostname (and any domains hosted on this server) always times out on hop 5, right between the two shown below:
76.246.22.2
(Request timed out.)
ggr7.sffca.ip.att.net [12.122.114.17]
The tracert eventually completes at hop 16. The addresses are all unique, and the timed out hop only occurs on hop 5. After the att.net, the hops are all some long hostname at above.net, before finally resolving to another IP, and then, finally, the hostname.
1) What does this timeout effect?
2) Is there anything I can do about this - or it something I've misconfigured? Dedicated CentOS/WHM server.
(The other IP's assigned to the same machine works without this timeout...)
It's just because router that is on Hop 5 is filtering traceroute request.
It's not a problem, there is no impact for your server and you can't do anything about this.