I ran into a strange situation. I use google DNS and exchange 2007 and I have had no problems getting into my mailbox. Now I can't get into my mailbox. When I remove the DNS entries for the google dns IP addresses I can open outlook with no problem. My question is how does Exchange use DNS in an AD environment? Why can't we use google DNS and our internal Active directory integrated DNS servers. I think it might have something to do with the srv and mx records? Thanks

are you pointing your Exchange server to google dns (in the TCP/IP settings of the Exchange server)? or are you using it for external DNS records management?

Exchange must be pointed to your Active Directory DNS servers for all functionality. This is how it locates Global Catalog servers and Domain Controllers. In fact, all computers and network devices in your internal network should point to yoru internal domain controllers. On your internal DNS servers, you can configure forwarders for all DNS entries it does not currently have, and this will cause your DNS server to go to the configured DNS server and cache the contents. This will vastly improve name resolution within your network and likely solve a host of other issues you may be having. Never setup your internal clients and servers to use External DNS.View my MCP Certifications

Makes sense. I was wondering what changes were made that caused outlook to not connect to the exchange servers eventhough previously (as in a couple of days ago) I could use google DNS servers.

Exchange has to be able to communicate with Active Directory which all relies on DNS to find the DC's and GC's. External DNS servers will not have that information so Exchange will have issues. In some cases I have seen where it won't even boot up all the way if it can't communicate with AD.