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This is driving me insane because I can't make head or tails of it.

We have two DCs (W2K3 SP1) and I'v tried this once on each machine as a sanity check.

DHCP is being served by either one of the machines and all machines get an address no problem. The servers can connect/ping/browse to the www and so can all our linux clients. But NONE of our windows clients (all windows 7).

I can do anything within the network, I can even ping the firewall/router but nothing from the windows clients is leaving the confines of our subnet.

I don't get it. The linux and windows clients are both served from the same DHCP server, the gateway is the same, everything is the same.

Anyone care to take a shot at how to resolve this?

I tried adding explicit routes at the clients, but still no go.

Some points that might help:

This is behind a SonicWall firewall (which I absolutely despise). The DCs are two VMs on two different boxes. DHCP being provided by these VMs. There is maybe 1/2 dozen other VMs that act as web or database servers and they can all connect to the internet. The issue happened this morning (my time is GMT +2) and I think its a result of issues on the VMs. The domain was built in what I can only kindly refer to as a patchy manner. Dealing with it is like running my cojones in a shredder.

Connection has proven to be an intermittent thing. On several of the Windows 7 clients, connection was restored for no obvious reason for a few minutes before it went away.

Nothing has been changed when it comes to domain policies for at least a few weeks now.

I can't think of anything else to add, but if there's something in specific, y'all just ask and I'll be more than happy to provide an answer.

TIA

SMIM

@John Gardeniers

I'm at home now so I'll post it tomorrow when I get to the office, but I did that when I was there and the gateway and DNS servers are right. DNS resolution is correct.

This is the ipconfig /all output on one of the clients that started to work magically after I turned off the DHCP

Windows IP Configuration

   Host Name . . . . . . . . . . . . : TAN-LEN-08
   Primary Dns Suffix  . . . . . . . :
   Node Type . . . . . . . . . . . . : Hybrid
   IP Routing Enabled. . . . . . . . : No
   WINS Proxy Enabled. . . . . . . . : No
   DNS Suffix Search List. . . . . . : tanasuk.lcl

********************************************************************
Wireless LAN adapter Wireless Network Connection:

   Connection-specific DNS Suffix  . : tanasuk.lcl
   Description . . . . . . . . . . . : Intel(R) WiFi Link 5100 AGN
   Physical Address. . . . . . . . . : 00-21-5D-77-8F-D2
   DHCP Enabled. . . . . . . . . . . : Yes
   Autoconfiguration Enabled . . . . : Yes
   Link-local IPv6 Address . . . . . : fe80::c864:eeb4:cb19:40cf%12(Preferred)
   IPv4 Address. . . . . . . . . . . : 192.168.186.151(Preferred)
   Subnet Mask . . . . . . . . . . . : 255.255.255.0
   Lease Obtained. . . . . . . . . . : Monday, January 17, 2011 9:48:50 AM
   Lease Expires . . . . . . . . . . : Monday, January 17, 2011 2:48:51 PM
   Default Gateway . . . . . . . . . : 192.168.186.1
                                       192.168.186.5
   DHCP Server . . . . . . . . . . . : 192.168.186.6
   DHCPv6 IAID . . . . . . . . . . . : 218112349
   DHCPv6 Client DUID. . . . . . . . : 00-01-00-01-14-4F-8A-A2-00-22-15-EB-3B-2F

   DNS Servers . . . . . . . . . . . : 192.168.186.5
                                       192.168.186.6
   Primary WINS Server . . . . . . . : 192.168.186.6
   NetBIOS over Tcpip. . . . . . . . : Enabled
********************************************************************

Ethernet adapter Local Area Connection:

   Media State . . . . . . . . . . . : Media disconnected
   Connection-specific DNS Suffix  . :
   Description . . . . . . . . . . . : Realtek RTL8168C(P)/8111C(P) Family PCI-E
 Gigabit Ethernet NIC (NDIS 6.20)
   Physical Address. . . . . . . . . : 00-22-15-EB-3B-2F
   DHCP Enabled. . . . . . . . . . . : Yes
   Autoconfiguration Enabled . . . . : Yes

Tunnel adapter Teredo Tunneling Pseudo-Interface:

   Media State . . . . . . . . . . . : Media disconnected
   Connection-specific DNS Suffix  . :
   Description . . . . . . . . . . . : Teredo Tunneling Pseudo-Interface
   Physical Address. . . . . . . . . : 00-00-00-00-00-00-00-E0
   DHCP Enabled. . . . . . . . . . . : No
   Autoconfiguration Enabled . . . . : Yes

Tunnel adapter isatap.tanasuk.lcl:

   Media State . . . . . . . . . . . : Media disconnected
   Connection-specific DNS Suffix  . : tanasuk.lcl
   Description . . . . . . . . . . . : Microsoft ISATAP Adapter #2
   Physical Address. . . . . . . . . : 00-00-00-00-00-00-00-E0
   DHCP Enabled. . . . . . . . . . . : No
   Autoconfiguration Enabled . . . . : Yes

Obviously, the one I tagged with asterisks is the one we're looking at.

Its right, the gateway should be and is 192.168.186.1, the DNS servers are 192.168.186.5|6 everything is right.

The weird thing is that things started to work after DHCP server was turned off! In my exasperated attempts, I even tried a linux server (CentOS 5.3 dhcpd) with the exact same results.

Any idea guys? I'm stumped and I'd LOVE to know what the heck is going on.

Here is the ipconfig /all output off of one of the DCs/DNS servers

Windows IP Configuration

   Host Name . . . . . . . . . . . . : TAN-SRV-DC2
   Primary Dns Suffix  . . . . . . . : tanasuk.lcl
   Node Type . . . . . . . . . . . . : Hybrid
   IP Routing Enabled. . . . . . . . : No
   WINS Proxy Enabled. . . . . . . . : No
   DNS Suffix Search List. . . . . . : tanasuk.lcl

Ethernet adapter Local Area Connection 2:

   Connection-specific DNS Suffix  . :
   Description . . . . . . . . . . . : Citrix XenServer PV Ethernet Adapter
   Physical Address. . . . . . . . . : A2-A9-A1-B4-FA-08
   DHCP Enabled. . . . . . . . . . . : No
   IP Address. . . . . . . . . . . . : 192.168.186.6
   Subnet Mask . . . . . . . . . . . : 255.255.255.0
   Default Gateway . . . . . . . . . : 192.168.186.1
   DNS Servers . . . . . . . . . . . : 192.168.186.5
                                       192.168.186.6

and this is off of my local linux laptop (ifconfig eth0)

eth0      Link encap:Ethernet  HWaddr 00:16:6f:55:07:e3  
          BROADCAST MULTICAST  MTU:1500  Metric:1
          RX packets:304 errors:0 dropped:0 overruns:0 frame:0
          TX packets:61 errors:0 dropped:5 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:47811 (47.8 KB)  TX bytes:12238 (12.2 KB)
          Interrupt:22 Memory:bc007000-bc007fff

(less /etc/resolv.conf)

# Generated by NetworkManager
nameserver 192.168.186.5
nameserver 192.168.186.6

and (route -n output)

Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
192.168.186.0   0.0.0.0         255.255.255.0   U     1      0        0 eth1
192.168.122.0   0.0.0.0         255.255.255.0   U     0      0        0 virbr0
169.254.0.0     0.0.0.0         255.255.0.0     U     1000   0        0 eth1
0.0.0.0         192.168.186.1   0.0.0.0         UG    0      0        0 eth1

As you can see, this is insane!

There is something I have noticed since the problem has now become intermittent. Some Windows 7 laptops will connect, others will not and some will connect for a bit and then just forget.

They connect perfectly fine locally. And though they have a gateway defined, its almost as if they don't know how to reach it. Trying a tracert, I get a timeout from the first hop, but not so on the *nix clients (CentOS, several Ubuntu, several Mac OS X). Could this be a DNS issue? as in both DCs aren't synching properly?

share|improve this question
    
Would you mind giving us a LOT more info - all you can think of please. –  Chopper3 Jan 16 '11 at 17:31
    
What kind of firewall? Can you post the config? –  Jason Berg Jan 16 '11 at 17:32
    
Please post the output of "ipconfig /all" from the Win7 machines. The description makes me wonder if they are getting the correct default gateway. –  John Gardeniers Jan 16 '11 at 22:43
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3 Answers

Start with the basics.

  1. Can the Windows 7 clients ping the DC's IP address?
  2. Can the windows 7 machines ping the gateway's IP address?
  3. Can the Windows 7 clients resolve DNS? (It sounds very much to me like this could a DNS related issue) Use nslookup to check this, not just ping.
  4. Check there are no bizarre group policies on the DC's that may be affecting network settings.
  5. Make sure that the Windows 7 systems are using the DC's as their primary nameserver.
share|improve this answer
    
Yes to all your questions and there are no policies that haven't been there for at least 2 months. –  Mustafa Ismail Mustafa Jan 16 '11 at 20:36
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Check proxy settings on the windows client.

Also check if there is firewall client installed (isa client).

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1  
We don't have ISA. Currently its SonicWall and the plan is to move on to pfSense when we have the time. –  Mustafa Ismail Mustafa Jan 16 '11 at 23:01
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OK, we found the culprit.

There was some SonicWall VPN adapter that was screwing things up. Disabling that brought balance back to the universe.

Thanks for everyone

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