connection issues to some domains and pop3

[Andy Steadman]

Hi all,

The server is running SBS2008 on a small network with 15 users. Every 2-4 days they will report that they cannot access the Internet or retrieve their POP3 emails (externally hosted). On investigation it seems that .co.uk addresses won't resolve but .com will. Outlook is reporting a connection error when trying to get the emails. A reboot and everything is back to normal.

I changed the DNS to use Google's DNS service and went through the connection wizards again but still the problem comes back.

Any ideas?

Andy

[TTr]

This is not a server error, it is an OS or network issue. You need to provide more details regarding your environment.

> they cannot access the Internet
> retrieve their POP3
> Outlook is reporting a connection error

What is this server's role?
What other servers are in the mix?
How do your users access the internet?
Where is outlook running and how does it get the emails?
How is the network setup?

[Andy Steadman]

Yes I realise it is not a server or OS issue and that I should be posting somewhere else maybe?

What is this server's role?
Domain Controller

What other servers are in the mix?
None (Small office setup)

How do your users access the internet?
Through a BT Business Router with wireless built in, DHCP turned off on the router.

Where is outlook running and how does it get the emails?
Locally on the PCs, connect to externally hosted via IMAP. Exchange is not cofigured on the server.

How is the network setup?
All PCs\Server\NAS Box\Printers\Router and Laptops connected to a single HP 24port GiG switch

[Matti_Kurkela]

My only Windows admin experience is from NT4 servers, but the symptoms would seem to point at the DNS server component in your SBS.

When the problem reappears, can you try stopping and restarting just the DNS service instead of rebooting the entire server? If it makes the problem go away, the fault would seem to be in the DNS service component.

(I don't know if restarting just the DNS component is even possible, as I understand the Active Directory has pretty strong ties to DNS.)

Is your SBS protected from external DNS requests and/or configured to reject them? Some security exploits rely on confusing a DNS server with maliciously-crafted requests. Your server should agree to resolve names for your users only, not to anybody external. Someone (or just a piece of worm-like malware) might be trying to attack you.

MK

[Andy Steadman]

I agree, I definately think it is a DNS issue, unfortunately I am not all too familiar with it.

It is possible to restart the DNS service, I will test that next time I have the problem.

The Internet connection is protected by the BT router which includes a firewall.

I think it is strange that it seemed to happen at almost identical times every 3 days, I was looking to see if a service is set to start then which may be having an impact but I could not find anything.

[Andy Baguley]

I've had this issue on two SBS 2008 installs.

It is tied in with DNS, and roots hints. The DNS fails after a few days.

I got around it on both by going back to DNS forwarders and manually entering DNS server addresses.

http://msmvps.com/blogs/bradley/archive/2009/06/29/how-to-flip-your-sbs-2008-to-forwarders.aspx