DNS: Search Domains not working correctly?
The domains in the search directive should be separated by whitespace only, not commas.  So replace

search loc1.sitea.example.net, loc2.sitea.example.net, loc1siteb.example.net


with

search loc1.sitea.example.net loc2.sitea.example.net loc1siteb.example.net


and try it again.  Note that in general it is better supported if you set these things up via System Preferences and then you don't get syntax problems like this.

System Preferences -> Network -> [Select the interface from the list on the left] -> Advanced... -> DNS -> Search Domains: