W2K Server, ISA2000 and DNS/Mail Routing Issues

[Bigtm]

Hello, I have been investigating a fault with one of my clients networks. In addition to other servers they have 2 dns servers(Main and Backup both w2k), A Mail server W2003, and a ISA 2000 proxy. Other servers include 2 ISA2004 servers acting as proxy's.

The problem is this. When the ISA 2000 server is taken offline the mail sever cant send out any mail and it takes ages to resolve incoming mail. Internet access is lost despite the fact that there is a replacemnt ISA 2004 servers deployed to take the place of the older ISA2000 server. In other words it seems that DNS resolution is slow or non existent and i cant find any indication, setup, configuration to indicate why this server is tied in to DNS.

When the server is put back online all returns to normal including email and internet. I have gone through the other servers and i cant find any specific setting to indicate that trafic is being routed through the older isa 2000 server.

Any help would be very welcome.

 

[ITPangaeaArchitect]

Are the machines in question configured as SecureNAT clients on ISA? AKA, do the machines point to the ISA 2000 server as a gateway?

-Brandon Wilson
MCSE00/03, MCSA:Messaging00, MCSA03, A+
Sr. Infrastructure Management Analyst
Distributed Systems Engineering
ACS, Inc.

 

[Bigtm]

Thank you for the response. The answer is no. The gateway is a linux firewall/proxy. None of the other servers are pointing to the ISA2000 server. There are dns rules and other trafic filtering rules set up on the ISA2000 server as part of the older setup but all the rules have been duplicated on the new ISA2004 servers. It makes no sense, Take the ISA2000 server of line and the entire network looses external access.

I have been through everuthing, cant figure it out but I do know that the ISA2000 server is not being used as a gateway.

BigTM.

 

[ITPangaeaArchitect]

isa 2000 and 2004 on the same segment with same routes, etc?

-Brandon Wilson
MCSE00/03, MCSA:Messaging00, MCSA03, A+
Sr. Infrastructure Management Analyst
Distributed Systems Engineering
ACS, Inc.