Reverse Proxy Woes

[Webflex]

I am using ISA as a reverse proxy behind a firewall (DMZ configuration)with one public IP address. Incoming requests are looked up in external DNS and routed to the ISA server.

All internal servers that are published have a destination set defined and a web publishing rule. For example;

1. Destination set mail-ab.domain.country has a name destination of mail-ab.domain.country.

Web publishing rule mail-ab.domain.country has an action to redirect to ip 123.456.678.1 (the option to send original host header is unticked)

2. Destination set xnet-ab.domain.country has a name destination of xnet-ab.domain.country.

Web publishing rule xnet-ab.domain.country has an action to redirect to ip 123.456.678.2 (the option to send original host header is unticked)

These two end up at the same destination - 2. !!

3. Destination set mail-cd.domain.country has a name destination of mail-cd.domain.country.

Web publishing rule mail-cd.domain.country has an action to redirect to ip 123.456.789.3 (different network)(the option to send original host header is unticked) - This works

The external DNS entries have 2 as an alias of 1.

Any thoughts as to why 1 and 2 end up at the same place.

Am I missing something obvious here?

TIA
Webflex