Hi,
I would not go as far as to say that using a Public DNS server is the answer but in some cases it helps.
Part of the issues is the IP numbers that these "Apple" Servers are on.
It appears the one that is highlighted and shows in the info Panel on the left is not actually Apple (despite the word Apple being part of the Name ( init.ess.apple.com )
Found by using Network Utility from the Applications/Utilities folder and using whois.ripe.net
% Note: this output has been filtered.
% To receive output for a database update, use the "-B" flag.
% Information related to '80.239.200.0 - 80.239.200.63'
inetnum: 80.239.200.0 - 80.239.200.63
netname: AKAMAI
descr: Akamai
org: ORG-AIB6-RIPE
country: SE
admin-c: RP8999-RIPE
tech-c: RP8999-RIPE
status: ASSIGNED PA
mnt-by: TELIANET-LIR
source: RIPE # Filtered
organisation: ORG-AIB6-RIPE
org-name: Akamai International B.V.
org-type: OTHER
descr: The Trusted Choice for Online Business
address: 8 Cambridge Center
address: MA02412 Cambridge
address: United States
phone: +1 6174443007
admin-c: NARA1-RIPE
tech-c: NARA1-RIPE
mnt-by: TELIANET-LIR
mnt-ref: TELIANET-LIR
source: RIPE # Filtered
Other options to "find" in the Whois do not find the servers.
This is the issue other DNS servers have.
The IMRemoteURLConnectionAgent.xpc (to give it it's full name) is part of the iMessage side of Messages beta.
IMAgent is used to login in Buddy Lists (Your old Style iChat ones) - It also does FaceTime.
The IMServivePlugInAgent is the Yahoo add on Plug-in stuff.
However I would point out that when this is seen it is usually the Buddy Lists that are either all not logging in or some are and some are not and therefore is not the iMessage side of Messages and is more likely something to do with IMAgent.
We know that for some users Force Quitting IMAgent (Use Activity Monitor) and then restarting Messages can help with this issue.
7:08 PM Monday; May 28, 2012
Please, if posting Logs, do not post any Log info after the line "Binary Images for iChat"
iMac 2.5Ghz 5i 2011 (Lion 10.7.4)
G4/1GhzDual MDD (Leopard 10.5.8)
MacBookPro 2Gb (Snow Leopard 10.6.8)
Mac OS X (10.7.4),
"Limit the Logs to the Bits above Binary Images." No, Seriously