DNS UDP port 0 activity

[Hooker, Bruce]

Howdy Folks,

The staff who support the firewalls at my site have asked
if I know anything about DNS/BIND sending queries from
port 53 to port 0.

Most of the DNS traffic monitored is the normal port 53 to
port 53 and high ports to port 53 but a significant amount
has a destination port of zero (0).

Our firewall is Firewall-1 from Checkpoint.

Any ideas?

Bruce Hooker