UDP DNS loadbalancing not Round Robin



  • Installed a PFSense device (running on VMWare) to provide firewall and load balancing protection to multiple DNS slave servers.  I'm running PFSense version: "2.1-BETA1 (amd64)
    built on Tue Mar 26 19:03:27 EDT 2013 FreeBSD 8.3-RELEASE-p6"

    I'm allowing UDP port 53 to the Loadbalance VIP but the LB monitor is watching TCP port 53 on the slave servers since you can't monitor UDP port 53.

    All that is working correctly.  Failover works correctly.  If the #1 slave server goes down ALL DNS requests go to the #2 slave server.  The problem is if both slave servers are up ALL DNS requests always go to slave server #1.  The connections are not being distributed to both slave servers.

    Is this a known issue?



  • Anyone seeing this issue?  I've tried with multiple installs and its an issue for sure.  Round Robin does not work on UDP DNS load balancing.


  • Rebel Alliance Developer Netgate

    When I first implemented that a couple years ago, it worked for me and others who tried it.

    What does your /var/etc/relayd.conf file look like?


Log in to reply