DNS sinkholing helps you to identify infected hosts
on the protected network using DNS traffic in situations where the
firewall cannot see the infected client's DNS query (that is, the
firewall cannot see the originator of the DNS query). In a typical
deployment where the firewall is north of the local DNS server,
the threat log will identify the local DNS resolver as the source
of the traffic rather than the actual infected host. Sinkholing
malware DNS queries solves this visibility problem by forging responses
to the client host queries directed at malicious domains, so that
clients attempting to connect to malicious domains (for command-and-control,
for example) will instead attempt to connect to a default Palo Alto
Networks sinkhole IP address (or to IP address that you define if
you choose to
Configure DNS Sinkholing
for a List of Custom Domains). Infected hosts can then be
easily identified in the traffic logs.