Support Central: KB #5039: ‘set holddown’ command blocking all recursive queries

[#1]

Problem Summary

The 'set holddown' command blocking all recursive queries

 

Customer Environment

Infoblox Grid running DNS service with global forwarders and 'set holddown' and forward-only clause enabled

 

Versions

All versions of NIOS

Cause

The 'set holddown' command cannot distinguish between a server or a forwarder and for this reason, all configurations are treated the same. Hence, all recursive queries may get 'held down'

 

Resolution

Disable the 'set holddown' command and instead use 'fetches-per-server' and 'fetches-per-zone' commands. 

The holddown feature (stop query to server with too many timeouts) does not take forwarders into account.  It should not be enabled on a server using forward only.  The fetches-per-server feature (limit queries in-flight to any given server) does take forwarders into account. However, if you have a global forwarder then it makes no sense at all to enable the feature.