Recursive queries fail if query source port is not fixed

[Hans F. Nordhaug]

* Steven Stromer <filter at stevenstromer.com> [2008-08-15]:
> I doubt that this is at all pertinent, but I was experiencing similar  
> behavior once I patched a client a few weeks ago and took them off  
> port 53. Recursive requests were failing three out of every four  
> times they were made, yet digs with trace worked. The company uses a  
> crappy Netgear firewall that I can't wait to trash. However, the fix  
> ended up coming from turning off tcp and udp flood protection on the  
> firewall. In this case the firewall was located between a DMZ area  
> and the company LAN, with the recursive nameserver located in the  
> DMZ, so the network was probably slightly different... 

This is exactly our network setup!

> However, the  symptoms sound so familiar that I thought I'd mention
> it. Maybe your  Cisco router is interpreting all the randomized UDP
> activity as a  flood. Apologies if this is off track with your issue
> - good luck  finding a fix!

I'll test this on Monday and report back - thx a lot for the
suggestion. 

Hans

PS! I wasn't at work yesterday so I haven't been able to test the
suggestions I got on Thursday. I'll report back here when/if I find a
solution.