Solved

IPv6 DNS took precedence over newer IPv4 assignment

Posted on 2014-03-04
7
3,750 Views
Last Modified: 2014-03-17
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
0
Comment
Question by:amigan_99
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 3
  • 3
7 Comments
 
LVL 50

Accepted Solution

by:
Don Johnston earned 500 total points
ID: 39905235
IPv6 lookups (A) are preferred over IPv6 (AAAA).

You can change this behavior though. But it depends on which OS you're running.  

For windows:
http://superuser.com/questions/436574/ipv4-vs-ipv6-priority-in-windows-7

If not, just google "prefer IPv4 DNS IPv6" and add your OS.
0
 
LVL 40

Expert Comment

by:footech
ID: 39905310
@donjohnston - I think you meant to say, "IPv6 lookups (AAAA) are preferred over IPv4 (A)."
:)
0
 
LVL 50

Expert Comment

by:Don Johnston
ID: 39905314
Yep.  Strikes again, Dyslexia does. :-)
0
Online Training Solution

Drastically shorten your training time with WalkMe's advanced online training solution that Guides your trainees to action. Forget about retraining and skyrocket knowledge retention rates.

 
LVL 1

Author Comment

by:amigan_99
ID: 39905443
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.
0
 
LVL 50

Expert Comment

by:Don Johnston
ID: 39906115
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.
0
 
LVL 1

Author Comment

by:amigan_99
ID: 39919703
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!
0
 
LVL 1

Author Closing Comment

by:amigan_99
ID: 39935632
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.
0

Featured Post

Get 15 Days FREE Full-Featured Trial

Benefit from a mission critical IT monitoring with Monitis Premium or get it FREE for your entry level monitoring needs.
-Over 200,000 users
-More than 300,000 websites monitored
-Used in 197 countries
-Recommended by 98% of users

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

You may have a outside contractor who comes in once a week or seasonal to do some work in your office but you only want to give him access to the programs and files he needs and keep privet all other documents and programs, can you do this on a loca…
Sometimes clients can lose connectivity with the Lotus Notes Domino Server, but there's not always an obvious answer as to why it happens.   Read this article to follow one of the first experiences I had with Lotus Notes on a client's machine, my…
This Micro Tutorial will teach you how to change your appearance and customize your Windows 7 interface to your unique preference. This will be demonstrated using Windows 7 operating system.
The Task Scheduler is a powerful tool that is built into Windows. It allows you to schedule tasks (actions) on a recurring basis, such as hourly, daily, weekly, monthly, at log on, at startup, on idle, etc. This video Micro Tutorial is a brief intro…

696 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question