A huge problem I ran into was DNS resolution. At my work we use a lot of internal subdomains for our systems. I usually work in 1 and sometimes in the second. Here's an example:
I usually work in loc1, so I set up the following search domains:
This means if I am looking for host1 it will try host1.loc1.example.com then host1.example.com. This works as expected. The problem is that I used to be able to look up host1.loc2 and it would do the right thing. This is not the case in OSX Lion. My guess is that it wouldn't append the search domain if the host your specified had a dot (.) in it.
Doing a google search lots of people have ran into the same problem, but the solutions all required a reboot. The best description was on this post on MacRumors. This got me there but I didn't want to reboot, so I tried to load up launchctl and restart com.apple.mDNSResponder with no luck. So I goofed around for a bit and found the following to work (after implementing the fix in the MacRumors post above -- go there first!):
$ sudo launchctl
launchd% unload /System/Library/LaunchDaemons/com.apple.mDNSResponder.plist
launchd% load /System/Library/LaunchDaemons/com.apple.mDNSResponder.plist
then check with:
ps aux | grep -i mdns
_mdnsresponder 2560 0.3 0.0 2481092 2832 ?? Ss 9:20PM 0:00.04 /usr/sbin/mDNSResponder -launchd -AlwaysAppendSearchDomains
Vola! Now all my DNS resolution works! Hope this helps anyone else having issues.