IPV6 address and I am not sure where it is coming from

I have a windows 2008R2 network.

Comcast came in and replaced the SMC modem I had with with a Cisco DPC3941B.  Now I have an issue where I can not join machines to AD.  My network does DCHP and DNS services for domain.  I have enclosed the Ipconfig /all.  

When you look at the DNS ipconfig /all  there are IPV6 address.  I looked them up they are Comcast addresses and they are before my DNS server.  I am not giving out any IPV6 and I believe these address will be looked at first.  I looked up these addresses and they are comcast DNS.  When I try to join machines to AD I get a DNS error I am attributing to these IPV 6 entries.  I am not using IPV6 in the network and IPV6 DNS enters are not checked in AD.

I really could use a second pair of eyes on this.  Comcast indicates this modem is not doing IPV6 and it is shut off.  I asked them to.  I have no firewall.  It is just the modem in bridge mode supposedly doing just NAT translation.  I think this thing is doing more that what it is supposed to and it is in bridge mode.  I went into the interface and checked.

Thanks very much for the help

Who is Participating?

[Product update] Infrastructure Analysis Tool is now available with Business Accounts.Learn More

I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

Jeff C.Network EngineerCommented:
Yes your correct.  IPv6 will be preferred over IPv4.  You can disable IPv6 on your PCs to test.
RickArnoldAuthor Commented:

I disabled IPV6 and now when I do Ipconfig /all it looks more normal but the DNS entry is missing see the txt file attachment.


RickArnoldAuthor Commented:
Diabale IPV6 on the workstation

Making Bulk Changes to Active Directory

Watch this video to see how easy it is to make mass changes to Active Directory from an external text file without using complicated scripts.

RickArnoldAuthor Commented:
The Comcast modem model is Cisco Model DCP3941B.  I have been doing a little looking on line and it seems like these modem give out IPV6 even if you disable it and it looks like it is disabled.


Jackie ManIT ManagerCommented:
There are no attachments.
Qlemo"Batchelor", Developer and EE Topic AdvisorCommented:
IPv6 works different from DHCP (in most cases), by soliciting settings. If you cannot shut up the Cisco to not offer IPv6 info, Comcast has to replace the device. No negotiations.

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
Windows Server 2008

From novice to tech pro — start learning today.