Strange Routing and Remote access and NAT problem - internet connectivity, Server 2003

Hello

I have a strange problem with a network I look after, here is the setup:

Server1: Runs as Domain Controller, DNS, Routing and Remote access as NAT providing desktops with internet connectivity, DHCP, DNS, 2 NICS: 1 internal, 1 external.

Server 2: Exchange and SQL server, 1 NIC connected direct to SDSL router.

Almost everyday the office looses internet connectivity, I can remote desktop to the domain controler but Internet Explorer does not have a connection, can ping external addresses though. Exchange works fine and desktops have access to shares on both machines. The exchange machine has a internet connection

Restarting the server does nothing to solve the problem, but eventually it will just start working again! There is nothing in the error logs for either machine. Restarting Routing and Remote access server does nothing either.

So in a nut shell:

NAT not working on Routing and Remote Access, no internet connection on Domain Controller but can access it through RDP and can ping external addresses, but Internet Explorer reports no connection. Restart does nothing, eventually starts working again on its own.

Any ideas?

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garethh86Asked:
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Raj-GTSystems EngineerCommented:
Remove the default gateway entry from NIC1 of Server1, and re-configure the DNS Server and remove any forwarders. I guess the issues you are having might be due to forwarders.

If the forwarded DNS servers failed, server1 and clients will loose the internet. The only explanation I can think for Server2 being able to browse is that either server1 DNS is not listening on the external NIC or the firewall is blocking the DNS traffic to Server1s external NIC, in which case Exchange will use the ISP DNS and continue to work.
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mlongohCommented:
If I have this right, the 2 servers have direct internet access, but all other machines (workstations) go through the RRAS NAT service?

When the outage occurs, browsing fails for users, but the Exchange server can still send/receive and therefore communicate via the Internet (so Internet connection is not down).

Can you open a browser on either server during the outage and browse without issue to Internet sites?
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mlongohCommented:
Oops, second read shows that you can't browse from the DC, but what about from the Exchange server?
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garethh86Author Commented:
Yes, I can browse from the Exchange server fine, this does not use RRAS NAT though, it is directly connected to the router which rules out any issue with the router its self.

The internet connection is still alive as I can RDP into the domain controller and from it I can ping external addresses, I just can't access web pages and either can the desktop machines (which go through RRAS NAT). They can however still send/recieve email through the exchange server and access shares on both machines.
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Raj-GTSystems EngineerCommented:
This sounds more like a DNS issues to me. Are you able to ping using the FQDNs during the issue?
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Raj-GTSystems EngineerCommented:
And also, are both servers configured to use the same DNS?
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garethh86Author Commented:
Yes, I can ping both machines, internally and externally using IP address and FQDN.

This is how the domain controller is set up:


NIC1-Internal:

192.168.0.200
255.255.255.0
192.168.0.200

Primary DNS: 192.168.0.200

NIC2-External:

87.x.x.x

DNS: 192.168.0.200
2nd DNS: DNS of ISP


Exchange machine:

Primary DNS: External IP of DC
2nd DNS: DNS of ISP


There are no errors for DNS in the event log apart from a dynamic update error that can be ignored if there are no other DNS servers in the network....which there aren't.
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mlongohCommented:
Well if the DC is failing to browse as well as the workstations, then it's NOT likely to be a NAT problem (the DC doesn't rely on NAT to communicate to the internet).

So you really have a periodic browsing outage on that device, the DC.  And I think that comparing the Exchange server's DNS and IP setup to the DC's is where I would start.  I'm guessing that the DC is using itself for DNS, but what' the Exchange server using for DNS?
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mlongohCommented:
Raj-GT is on the right track.  I'd also just do an NSLOOKUP from the Exchange server and see if you get any errors as it tries to connect to the DNS server service on the DC.
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garethh86Author Commented:
Was indeed a DNS issue, has been up for over a week now without any problems. Thanks!
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