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Domain Controller DNS issue - No internet for us all..

jmair

By jmair
in Windows Server 2008 R2

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jmair

jmair

Posted
Posted

Looks like I lost internet connection on our network. I'm certain that it's our domain controllers but I can't see why it has stopped working at 3am a week ago.

I've been looking for the root of this problem and can not find it. Hoping an extra pair of eyes (you) may have a suggestion.

 

Here's what I know

  • My laptop pointing to the gateway and using our isp as a dns gets internet. So this is not an isp issue.
  • Both domain controllers can ping eachother and from what I can tell, everything internally works fine.
  • nslookup msn.com often times out.. then out of nowhere it returns just fine.
  • firewall and filter have been taken out of the loop (I was really hoping one of them were causing the problem)
  • Domain controllers have timeout errors on the forwarders - the ISP dns server ips. ISP confirmed they should be fine.
  • No recent changes have been made.

 

 

PDC: 10.1.1.2

BDC: 10.1.1.0

 

Here is the ipconfig /all of my PDC

 

Windows IP Configuration

 

Host Name . . . . . . . . . . . . : como2010

Primary Dns Suffix . . . . . . . : parkcounty.int

Node Type . . . . . . . . . . . . : Hybrid

IP Routing Enabled. . . . . . . . : No

WINS Proxy Enabled. . . . . . . . : No

DNS Suffix Search List. . . . . . : parkcounty.int

 

 

Ethernet adapter Local Area Connection:

 

Connection-specific DNS Suffix . :

Description . . . . . . . . . . . : Broadcom NetXtreme Gigabit Ethernet

Physical Address. . . . . . . . . : 00-14-5E-EB-00-D3

DHCP Enabled. . . . . . . . . . . : No

Autoconfiguration Enabled . . . . : Yes

IPv4 Address. . . . . . . . . . . : 10.1.1.2(Preferred)

Subnet Mask . . . . . . . . . . . : 255.255.248.0

Default Gateway . . . . . . . . . : 10.1.1.254

DNS Servers . . . . . . . . . . . : 10.1.1.0

10.1.1.2

127.0.0.1

NetBIOS over Tcpip. . . . . . . . : Enabled

 

 

Thank you kindly for any suggestions!

jmair

jmair

Posted
  • Author
Posted

Here's an example if it acting wierd. Forwarders may resolve, but connection clearly isn't reliable. ((from my machine though at the same d-mark and same gateway, I have no issues.))

[ATTACH=CONFIG]17748[/ATTACH]

jmair

jmair

Posted
  • Author
Posted

nslookup google.com

Server: como2012.parkcounty.int

Address: 10.1.1.0

 

DNS request timed out.

timeout was 2 seconds.

DNS request timed out.

timeout was 2 seconds.

 

------

tracert google.com

Unable to resolve target system name google.com

 

 

[*] DNS services up and running. Forgot to add that in the op

plexer

plexer

Posted
Posted
nslookup google.com

Server: como2012.parkcounty.int

Address: 10.1.1.0

 

DNS request timed out.

timeout was 2 seconds.

DNS request timed out.

timeout was 2 seconds.

 

------

tracert google.com

Unable to resolve target system name google.com

 

 

[*] DNS services up and running. Forgot to add that in the op

 

What version of server are you running?

 

You really have a server with .0 ip address?

 

Ben

jmair

jmair

Posted
  • Author
Posted
I had an odd issue when RM changed an IP address of their server. I needed to remove the old ip and manually add the new one in DNS forwarders.

 

Not much of a dns wizard but it may help.

 

I just tried that. I added my ISP secondary DNS servers.. You know when you input the ips and it resolves the fqdn quickly, this takes a very long time. On the server, I'm pinging another network device ping (10.1.1.12 -t) and see no delay or drops.

jmair

jmair

Posted
  • Author
Posted
What version of server are you running?

 

You really have a server with .0 ip address?

 

Ben

 

Windows Server 2008 R2 Standard.. And yes.. My BDC is 10.1.1.0.. best practice analyzer hasn't yelled at me yet =)

plexer

plexer

Posted
Posted
Windows Server 2008 R2 Standard.. And yes.. My BDC is 10.1.1.0.. best practice analyzer hasn't yelled at me yet =)

 

Ok just got confused with you reffering to them as a pdc and bdc as there is no longer such a thing anymore all 2008 R2 are full replica domain controllers.

 

DNS is configure and replicated on both servers?

 

Ben

jmair

jmair

Posted
  • Author
Posted
From Server...

 

what happens when you ping 8.8.8.8 ?

 

Rob

 

times out. My laptop going through the same gateway pings it just fine. Somethings funky on the server for sure. Also double checked, Windows Firewall service is disabled and stopped.

plexer

plexer

Posted
Posted

What happens if you set dns on server to be just 8.8.8.8 and then try to ping it?

 

Default gateway on servers is correct?

 

DNS forwarders in DNS are set correctly?

 

Ben

twin--turbo

twin--turbo

Posted
Posted
times out. My laptop going through the same gateway pings it just fine. Somethings funky on the server for sure. Also double checked, Windows Firewall service is disabled and stopped.

 

 

So it's not a DNS issue then.

 

Tracert to 8.8.8.8 , see where it gets to.

 

Do it on the other server as well.

 

 

Rob

jmair

jmair

Posted
  • Author
Posted
What happens if you set dns on server to be just 8.8.8.8 and then try to ping it?

 

Default gateway on servers is correct?

 

DNS forwarders in DNS are set correctly?

 

Ben

 

Thanks for the help guys. I am very grateful.

 

When I set the servers nic dns to 8.8.8.8 I can ping 8.8.8.8

 

default gateway is fine. double checked dns forwarders and even swapped with isp second set of dns servers to see if that would make any difference.

jmair

jmair

Posted
  • Author
Posted
What happens if you set dns on server to be just 8.8.8.8 and then try to ping it?

 

Default gateway on servers is correct?

 

DNS forwarders in DNS are set correctly?

 

Ben

 

Thanks for the help guys. I am very grateful.

 

When I set the servers nic dns to 8.8.8.8 I can ping 8.8.8.8

 

default gateway is fine. double checked dns forwarders and even swapped with isp second set of dns servers to see if that would make any difference.

jmair

jmair

Posted
  • Author
Posted
So it's not a DNS issue then.

 

Tracert to 8.8.8.8 , see where it gets to.

 

Do it on the other server as well.

 

 

Rob

 

the laptop bypasses our networks dns server. Any other computer that uses our server has the connectivity problem same as the dns server.

plexer

plexer

Posted
Posted

Is this all from the server with the .0 ip address or is the other one the same? From the other server remove the .0 one as a dns server and try?

 

On the .0 server remove all other dns servers apart from the the other dc and try again?

 

Ben

jmair

jmair

Posted
  • Author
Posted

Just so I'm clear, because I'm at a point that I'm questioning everything.

on the nic of the server, the dns should be the ips of the internet dns servers.. correct? And we use the DNS forwarders as the only location to ass the isp DNS server (or external dns server ips)

plexer

plexer

Posted
Posted

No in a fully functioning ad domain your domain controllers and all pc's should have their dns servers set to be the domain controllers and nothing else.

 

Working DNS is the cornerstone of Active Directory.

 

The DNS servers can then use root hints or a dns forwarder to resolve ip addresses for names in the outside world.

 

Getting you to change them was only as a test of trying to pin down where the issue is.

 

Ben

jmair

jmair

Posted
  • Author
Posted
No in a fully functioning ad domain your domain controllers and all pc's should have their dns servers set to be the domain controllers and nothing else.

 

Working DNS is the cornerstone of Active Directory.

 

The DNS servers can then use root hints or a dns forwarder to resolve ip addresses for names in the outside world.

 

Getting you to change them was only as a test of trying to pin down where the issue is.

 

Ben

 

(I was referring to my own wacky brain, I've been juggling these for 16hrs trying to get our school back up, apparently me shouting at the machine "you're setup correctly work" doesn't work.)

 

BTW, I did try dropping the .0 and nothing has changed for the good. I'm currently shutting down one of the servers and will play around with everything I can find. It's also the one time that the event logs aren't yelling at me about a glaring issue. Go figure.

apeman

apeman

Posted
Posted
No in a fully functioning ad domain your domain controllers and all pc's should have their dns servers set to be the domain controllers and nothing else.

 

Working DNS is the cornerstone of Active Directory.

 

The DNS servers can then use root hints or a dns forwarder to resolve ip addresses for names in the outside world.

 

Getting you to change them was only as a test of trying to pin down where the issue is.

 

Ben

 

I agree, this is how it should be configured as long as your DNS services are running on your DC's.

If DNS is on the DC's then the Primary DNS server listed on the network Adapter should be one of your other DNS/DC server and its own IP its Secondary DNS server

 

You also have to update your list of root hint servers manually, an up to date list can be found here ftp://ftp.rs.internic.net/domain/db.cache.

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