Plesk 12.5 DNS Server Stopped Responding Overnight

[Olly]

I've come into work this morning to find all our websites are down because Plesk isn't responding to DNS requests externally.

I've tried restarting the DNS service, and reinstalling it. Running a portscan to our IP shows that the DNS port is open.

If you SSH into the server and run "nslookup whitesweb.co.uk 127.0.0.1" it returns the correct response, any ideas what might be causing this?

 

[IgorG]

Are you sure that port 53 is not firewalled?

 

[Olly]

I'm sure, "Domain name server" has a tick against it, and this morning I opened "System policy for incoming traffic" to rule out the firewall.

 

[IgorG]

So, can you connect to this server outside with

telnet servername.com 53

?

 

[Olly]

I can, you just get a flashing cursor and then it disconnects after about 30 seconds.

 

[IgorG]

Well. This means that DNS port 53 is not accessible on your Plesk server. I suggest you check your network infrastructure, firewalls, routers, etc.