IPv6 DNS took precedence over newer IPv4 assignment
Had a strange thing happen. I have an HP laptop with Win 7. I got onto the WiFi network at work which is just bridging the data subnet. But oddly the expected local IPv4 DNS server was not taking priority as viewed by nslookup. I think that may be my home comcast assigned DNS.
So the question is: Can I make IPv4 addressing and assigned DNS always take priority over IPv6? The way I dealt with the immediate issue was to just disable IPv6 on the wifi nic. That worked. But wonder if there's a more subtle approach I could take.
U:\>nslookup
Default Server: UnKnown
Address: 2001:558:feed::1
So the question is: Can I make IPv4 addressing and assigned DNS always take priority over IPv6? The way I dealt with the immediate issue was to just disable IPv6 on the wifi nic. That worked. But wonder if there's a more subtle approach I could take.
U:\>nslookup
Default Server: UnKnown
Address: 2001:558:feed::1
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Yep. Strikes again, Dyslexia does. :-)
ASKER
Seems we're on the right track. But the issue I was seeing here was somewhat different. It's not that DNS was resolving to IPv6 addresses. It's that the DNS server that Windows 7 had decided to use was at an IPv6 owned by Comcast. And I had never hard set that DNS server in my TCP/IP properties. In fact I had gone to entirely different network (work) which hands out a v4 IP address and a local v4 defined DNS server. Yet my system kept insisting on using that IPv6 DNS server despite reboot, despite ipconfig /release and renew and /dnsdflush. The only thing that worked was going into wifi adapter properties and unchecking the IPv6 box. Then everything sorted itself out.
I guess I'm not following you.
If there is any IPv6 DNS server, your host will use that to resolve a domain name. You got the DNS server through DHCP.
If there is any IPv6 DNS server, your host will use that to resolve a domain name. You got the DNS server through DHCP.
ASKER
Oops - hadn't responded in a while. Following up..
The IPv6 DNS information must have come from my home and not from the DHCP servers at work. At least that would be a viable theory. I have Comcast at home so I could see the laptop grabbing an IPv6 Comcast IP and DNS from the Comcast (XFinity) router. But what I'm saying is - the next day I go into work. I know that the work networks have no direct connection to Comcast anything. The DHCP server at work hands me an IPv4 address (and perhaps an IPv6) and yet I still have that comcast IPv6 DNS server. The DHCP servers at work have no knowledge of that DNS server. Yet it keeps coming back like a crazy ex girlfriend!
The IPv6 DNS information must have come from my home and not from the DHCP servers at work. At least that would be a viable theory. I have Comcast at home so I could see the laptop grabbing an IPv6 Comcast IP and DNS from the Comcast (XFinity) router. But what I'm saying is - the next day I go into work. I know that the work networks have no direct connection to Comcast anything. The DHCP server at work hands me an IPv4 address (and perhaps an IPv6) and yet I still have that comcast IPv6 DNS server. The DHCP servers at work have no knowledge of that DNS server. Yet it keeps coming back like a crazy ex girlfriend!
ASKER
I didn't really solve the mystery in full and I don't want to go through the process of recreating the environment with the failed state. But this is very helpful information for dealing with IPv6 generally in the future. Thank you.
:)