pix 520 brakes dns for some reason 1

[8624]

We are moving our network to a different subnet.
There are a lot of people using the network and we can’t afford to take the firewall down.
So we have a old pix 520 in the store room and two 525s functioning in a state full failover mode. I installed ver 6.22 IOS on the 520. did a write erase and copied the same exact configuration from the 525 into the 520 and did a wr mem, but once we turned off the 525 firewall and plugged the 520 in place of it. Internal DNS works. I could access the citric server via the ice client, but external DNS will not work. We could not receive our pop mail. Users could not get to the website. I replaced the PIX 520 firewall with the PIX 525 and everything starts working again try this many time same results.

Can anyone help me with this problem?

 

[yizhar]

HI.

The perimeter router might have a dirty ARP entry in cache.
You should reboot the router or clear its ARP table when you replace the pix device.


Yizhar Hurwitz

http://come.to/yizhar

http://teachers.sivan.co.il/yizhar

 

[havanajoe]

Hi there,

I agree with yizhar, the problem is the perimeter router. The ARP cache is looking for the MAC address of the previous PIX not the new one. I ran into the same problem when I moved from one pix to another. Once I rebooted the perimeter router all of the traffic flowed as it should.