Recommended DNS setup for an ISA/Forefront TMG server

I have a Forefront 2010 server in place as a web proxy server. Every few weeks, I notice that our web monitoring server reports false alarms and outages.The 'outages' last for about a minute, then return to normal.
Usually this is resolved by restarting the ISA server, or moving around the DNS server preference order.
My question is this: What is the recommended/best practice DNS setup. THe ISA/Forefront has a LAN and a WAN nic. Currently, I have the LAN nic set to use the internal DCs for DNS and also the ISP DNS servers as a lower priority. The WAN nic uses our ISP DNS servers.

I have read in some docs that it is better to install DNS on the ISA server and let it handle DNS itself, instead of the internal DNS servers doing it?
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sherryfitzgroupAsked:
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ChrisLead Infrastructure ArchitectCommented:
the recommended setup for TMG where you have two nics one internal and one external is that the external NIC has a default gateway and no DNS and the internal NIC has no gateway and internal DNS and you make sure your internal DNS works fine.

you would then put static routes back to the internal networks. I wouldn't install a DNS server on your ISA server.

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sherryfitzgroupAuthor Commented:
Thanks for your input. I already have the LAN nic with no gateway.
If I change the WAN nic to have no DNS and just a gateway (in this case a Cisco ASA), where do the DNS requests go from it?
Does it just use the DNS servers of the ASA?
ChrisLead Infrastructure ArchitectCommented:
No it will use internal DNS to resolve the address the then route according to the routing table.
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Keith AlabasterEnterprise ArchitectCommented:
NO....

The ISA will look to the internal DNS server, same as the internal clients will.
The internal DNS servers use the lookups of your ISP set within the DC dns manager.
Keith AlabasterEnterprise ArchitectCommented:
just make sure you have an access rule allowing DNS from localhost to internal.
sherryfitzgroupAuthor Commented:
great thanks-hopefully it will stop the 'outages' reported by our monitoring server
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Microsoft Forefront ISA Server

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