[Opensim-dev] DNS lookup and caching

[Michael Heilmann]

OpenSim Devs

In the region configs, if you use a hostname instead of an IP address, 
Opensimulator will resolve it to an IP address immediately, passing the 
IP address to the client instead of the hostname. Looking in the code, I 
found a comment about xml-rpc and mono dns caching, but little else.  
Looking online, mono appears to cache DNS names for too long, and 
changing the DNS cache refresh rate is not yet implemented -- but I 
don't understand why resolving once and using the IP address instead 
would solve that.

The MOSES Opensimulator Grid has over 100 regions on 10 hosts running on 
a local LAN with internet connecting clients.  Our enterprise firewall 
does not allow network hairpinning (servers refer to themselves or other 
servers using external IP addresses). We have worked around this by 
adding a VLAN, where servers can address eachother directly using their 
external ip addresses.  This has mostly worked, but hosting an internal 
nameserver would be much more desirable.  We are also forced to rely on 
the IT guys in charge of the firewall and the switch to change anything, 
and that is less reliable than we want.  An internal nameserver we can 
do ourselves.

Can anyone explain the xml-rpc / mono dns caching problem that was fixed 
by resolving the hostname and using the IP instead?  Is there a 
persisting reason that hostname functionality has not been restored?  Thanks

-- 
Michael Heilmann
Research Associate
Institute for Simulation and Training
University of Central Florida