If all tye needs is the IP address you are going to for perlmonks, then Wireshark seems like overkill. See if this Firefox plugin works: ShowIP

I was going to say just run nslookup perlmonks.org (works in Windows, too) and the response is probably the cached answer that Firefox is using, but I'm honestly not certain that is true. Firefox does not necessarily use the DNS resolver libs on the OS.