Reducing DNS lookups

David Hartburn D.J.Hartburn at
Tue Feb 21 13:10:51 CET 2017


For our LDAP queries, we have specified the forest DNS name as the LDAP 
server, so that we achieve via DNS a random distribution of queries 
against our AD servers. Previously we had hammered the first server on 
the list.

This has kept our AD guys happy, but we have noticed that at busy times 
our FR servers are doing over 100 DNS queries per second, for the same 

I can not spot anything in the FreeRADIUS config files, but is there any 
way to reduce the number of DNS lookups? We are running 3.0.12 on RHEL7.

Outside of FreeRADIUS, we could either make sure each server has a 
different /etc/hosts file, which is not ideal, or implementing local DNS 
caching seems to be the more sensible way to go. Are there any other 
alternatives other people are using?


Dave Hartburn

More information about the Freeradius-Users mailing list