Bind attempting to connect to invalid servers on port 53
Issue
Our main DMZ DNS servers have experienced sporadic outages due to them being blackholed by the firewall for attempting to connect to unauthorized servers on port 53.
The IP networks in question are:
Internal: 10.0.0.0
DMZ: 192.168.0.0
The DMZ DNS servers are being blackholed trying to get to port 53 on systems in our stores (e.g. 10.4.1.0, 10.2.1.0, etc)
The question I'm trying to answer is how is it possible to get a bind server to attempt a name lookup on system that is not listed as a nameserver in any configuration file, inlcuding the root hints?
Environment
Red Hat Enterprise Linux bind DNS server
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