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 192.168.1.11 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

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

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.

Thanks,

Rick
RickArnoldAuthor Commented:
Diabale IPV6 on the workstation

Rick
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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.

Thanks,

Rick
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.

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