Fail over problem

[Adrian Chapela <achapela.rexistros@xxxxxxxxx>]

Hello,  I have a two directors in high availability configuration. All 
it's OK for TCP, but for UDP it's no OK. In UDP load balance it's ok, 
but the fail over don't happens.  If one client is "redirected" to one 
real server, the connections are redirected always to this server, even 
the server goes down.
Could be a bug ?? A linux virtual server problem ?? I probe this with 
two DNS servers.
The config:

virtual_server 192.168.19.41 53  {
 delay_loop 6
 lb_algo wrr
 lb_kind DR
 persistence_timeout 30
 protocol UDP

 real_server 192.168.19.143 53 {
     weight 100
     MISC_CHECK {
              misc_path "/usr/bin/dig example.es @192.168.19.143 
+time=5  +tries=5 +fail > /dev/null"
              misc_timeout 6
     }
 }

 real_server 192.168.19.144 53 {
     weight 100
     MISC_CHECK {
              misc_path "/usr/bin/dig example.es @192.168.19.144 
+time=5  +tries=5 +fail > /dev/null"
              misc_timeout 6
     }
 }
}