IP Port/filtering/filrewall info?

[Dave Carmean]

Sorry, I thought I saw this discussion recently but I've been unable 
to find the thread.

It seems as if the default (UDP) source port behavior for server-to-server 
queries has changed recently.  Specifically, I have one set of 
servers running 8.2.1, which seem to send queries from a random 
high-numbered port (which my firewall passes), whereas a new set of 
servers running 8.2.2-P5 seem to want to send from port 53 (which 
are blocked, for reasons known only to somebody deep inside IT from 
ages ago :o).

Another way to ask the question is: Is the information on proxying and/
or filtering DNS, contained in Chapman and Zwicky's _Building Internet 
Firewalls_ (1st ed.), still correct?

Thanks.