Dns – Confusion about DNS Suffixes with VPN

dnsvpn

So on my home network I run my own domain controller & DNS server. On my client machine (which is a member of this home domain), I connect to my work VPN and from that point my DNS messes up.

My internet works because I unchecked "Use default gateway on remote network", so that's not a problem. I also have explicitly set the primary DNS suffix of my NIC (Local Area Connection 2) to dailey.home.com, since that is the domain of my internal network. Ideally I don't want to manually set it, but I did it anyway because I thought it might help.

Before I connect to my VPN, my ipconfig /all for "Windows IP Configuration" looks like this:

Windows IP Configuration

   Host Name . . . . . . . . . . . . : Bob
   Primary Dns Suffix  . . . . . . . : dailey.home.com
   Node Type . . . . . . . . . . . . : Hybrid
   IP Routing Enabled. . . . . . . . : No
   WINS Proxy Enabled. . . . . . . . : No
   DNS Suffix Search List. . . . . . : dailey.home.com

When I connect to my VPN, then it changes to this:

Windows IP Configuration

   Host Name . . . . . . . . . . . . : Bob
   Primary Dns Suffix  . . . . . . . : dailey.home.com
   Node Type . . . . . . . . . . . . : Hybrid
   IP Routing Enabled. . . . . . . . : No
   WINS Proxy Enabled. . . . . . . . : No
   DNS Suffix Search List. . . . . . : dailey.home.com
                                       pacs.local

My router, which is my default gateway on my home network, has the domain name "router", which points to 10.3.1.1. When I type "router" into my browser (BEFORE connecting to my VPN), I correctly reach my router's HTTP firmware page.

After I connect to the VPN, I do NOT reach the firmware page. When I run a PING on "router", it no longer says 10.3.1.1, but instead has an IP address of 66.114.124.140, which I don't recognize.

In fact, when I try to use ANY local DNS name I have setup, such as computer names or the name of my printer, NONE of them work while the VPN is connected. The IP address is the same for all of them: 66.114.124.140. In fact, if I try a domain name that doesn't even exist, I still get a response from the same IP address.

While connected to the VPN, nslookup for my 'router' returns this (even for a fake domain name!):

C:\Users\robert>nslookup router
Server:  svitdc03.pacs.local
Address:  172.16.0.56

Non-authoritative answer:
Name:    router.dailey.home.com
Address:  66.114.124.140

With the VPN disconnected, nslookup for 'router' returns the expected results:

C:\Users\robert>nslookup router
Server:  server.dailey.home.com
Address:  10.3.1.120

Name:    router.dailey.home.com
Address:  10.3.1.1

Why is this happening? I don't quite understand. Below is the rest of my IPCONFIG results, with the VPN included.

Windows IP Configuration

   Host Name . . . . . . . . . . . . : Bob
   Primary Dns Suffix  . . . . . . . : dailey.home.com
   Node Type . . . . . . . . . . . . : Hybrid
   IP Routing Enabled. . . . . . . . : No
   WINS Proxy Enabled. . . . . . . . : No
   DNS Suffix Search List. . . . . . : dailey.home.com
                                       pacs.local

PPP adapter True Automation:

   Connection-specific DNS Suffix  . : pacs.local
   Description . . . . . . . . . . . : True Automation
   Physical Address. . . . . . . . . :
   DHCP Enabled. . . . . . . . . . . : No
   Autoconfiguration Enabled . . . . : Yes
   IPv4 Address. . . . . . . . . . . : 172.16.0.196(Preferred)
   Subnet Mask . . . . . . . . . . . : 255.255.255.255
   Default Gateway . . . . . . . . . :
   DNS Servers . . . . . . . . . . . : 172.16.0.56
                                       172.16.0.42
   NetBIOS over Tcpip. . . . . . . . : Enabled

Ethernet adapter Local Area Connection 2:

   Connection-specific DNS Suffix  . : dailey.home.com
   Description . . . . . . . . . . . : Realtek PCIe GBE Family Controller #2
   Physical Address. . . . . . . . . : 00-1F-BC-01-55-34
   DHCP Enabled. . . . . . . . . . . : Yes
   Autoconfiguration Enabled . . . . : Yes
   IPv4 Address. . . . . . . . . . . : 10.3.1.31(Preferred)
   Subnet Mask . . . . . . . . . . . : 255.255.255.128
   Lease Obtained. . . . . . . . . . : Sunday, May 01, 2011 11:25:58 AM
   Lease Expires . . . . . . . . . . : Monday, May 02, 2011 11:25:59 AM
   Default Gateway . . . . . . . . . : 10.3.1.1
   DHCP Server . . . . . . . . . . . : 10.3.1.1
   DNS Servers . . . . . . . . . . . : 10.3.1.120
                                       208.67.222.222
   NetBIOS over Tcpip. . . . . . . . : Enabled

Ethernet adapter Local Area Connection:

   Media State . . . . . . . . . . . : Media disconnected
   Connection-specific DNS Suffix  . :
   Description . . . . . . . . . . . : Realtek PCIe GBE Family Controller
   Physical Address. . . . . . . . . : 00-1F-BC-01-55-35
   DHCP Enabled. . . . . . . . . . . : Yes
   Autoconfiguration Enabled . . . . : Yes

Tunnel adapter isatap.dailey.home.com:

   Connection-specific DNS Suffix  . : dailey.home.com
   Description . . . . . . . . . . . : Microsoft ISATAP Adapter
   Physical Address. . . . . . . . . : 00-00-00-00-00-00-00-E0
   DHCP Enabled. . . . . . . . . . . : No
   Autoconfiguration Enabled . . . . : Yes
   Link-local IPv6 Address . . . . . : fe80::5efe:10.3.1.31%12(Preferred)
   Default Gateway . . . . . . . . . :
   DNS Servers . . . . . . . . . . . : 10.3.1.120
                                       208.67.222.222
   NetBIOS over Tcpip. . . . . . . . : Disabled

Tunnel adapter isatap.{4827DF55-4B5E-405B-BE43-9B40BB4D7804}:

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

Tunnel adapter Local Area Connection* 9:

   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.pacs.local:

   Media State . . . . . . . . . . . : Media disconnected
   Connection-specific DNS Suffix  . : pacs.local
   Description . . . . . . . . . . . : Microsoft ISATAP Adapter #3
   Physical Address. . . . . . . . . : 00-00-00-00-00-00-00-E0
   DHCP Enabled. . . . . . . . . . . : No
   Autoconfiguration Enabled . . . . : Yes

Best Answer

When you are connected to your VPN, DNS queries are being handled by your office's servers. When you query for "router", your computer is adding the suffix pacs.local. For whatever reason, your office's DNS servers appear to respond with 66.114.124.140 for any domain they don't know about.

Try running nslookup router 10.3.1.120, you should get back the correct IP address for your router because your local DNS server will be doing the address resolution.

It sounds like what you want is the same as the asker in this Server Fault question: you have multiple NICs on a computer (one is a virtual NIC), and you want DNS resolution to first try your local DNS servers, then try the remote DNS servers if that fails. That person's issue was resolved by changing the order of network adapters as described in Microsoft KB894564, so perhaps that will work for you as well.

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