DHCP/DNS problems when migrating computers

Hi all,

We recently merged with another company and we are trying to merge their
users and computers into our forest. So far the testing has mostly gone
smoothly, but I had one problem with my test of migrating a workstation.

The source domain uses Active Directory DHCP. The target domain uses a DHCP
server on a Cisco router. When I migrated the computer, it continued to get
a DHCP address from the source domain's DC, along with the source domain's
DNS servers. Therefore it didn't register itself properly with the target
domain's DNS servers; the workstation appeared in both domains but was
inaccessible from either. We had to manually set the IP, gateway, and DNS.

Can anyone give me any advice on how we can handle this problem?

Thanks,
- Steve

Hello Steve,

Both DHCP servers are on thesame subnet? Well, then first come first serve.

Best regards

Meinolf Weber
Disclaimer: This posting is provided "AS IS" with no warranties, and confers
no rights.
** Please do NOT email, only reply to Newsgroups
** HELP us help YOU!!! http://www.blakjak.demon.co.uk/mul_crss.htm


> Hi all,
>
> We recently merged with another company and we are trying to merge
> their users and computers into our forest. So far the testing has
> mostly gone smoothly, but I had one problem with my test of migrating
> a workstation.
>
> The source domain uses Active Directory DHCP. The target domain uses
> a DHCP server on a Cisco router. When I migrated the computer, it
> continued to get a DHCP address from the source domain's DC, along
> with the source domain's DNS servers. Therefore it didn't register
> itself properly with the target domain's DNS servers; the workstation
> appeared in both domains but was inaccessible from either. We had to
> manually set the IP, gateway, and DNS.
>
> Can anyone give me any advice on how we can handle this problem?
>
> Thanks,
> - Stev

Steve,
have you considered configuring DNS Server via a GPO linked to the OU
hosting migrated comptuers in the target domain? This would take precedence
over the the setting assigned through DHCP. For more info, refer to
http://support.microsoft.com/kb/294785

hth
Marcin

"Steve Kadish" <> wrote in message
news:2DA76775-52A8-4C74-9D0B-...
> Hi all,
>
> We recently merged with another company and we are trying to merge their
> users and computers into our forest. So far the testing has mostly gone
> smoothly, but I had one problem with my test of migrating a workstation.
>
> The source domain uses Active Directory DHCP. The target domain uses a
> DHCP
> server on a Cisco router. When I migrated the computer, it continued to
> get
> a DHCP address from the source domain's DC, along with the source domain's
> DNS servers. Therefore it didn't register itself properly with the target
> domain's DNS servers; the workstation appeared in both domains but was
> inaccessible from either. We had to manually set the IP, gateway, and
> DNS.
>
> Can anyone give me any advice on how we can handle this problem?
>
> Thanks,
> - Steve
>
>

In news:2DA76775-52A8-4C74-9D0B-,
Steve Kadish <>, posted the following:
> Hi all,
>
> We recently merged with another company and we are trying to merge
> their users and computers into our forest. So far the testing has
> mostly gone smoothly, but I had one problem with my test of migrating
> a workstation.
>
> The source domain uses Active Directory DHCP. The target domain uses
> a DHCP server on a Cisco router. When I migrated the computer, it
> continued to get a DHCP address from the source domain's DC, along
> with the source domain's DNS servers. Therefore it didn't register
> itself properly with the target domain's DNS servers; the workstation
> appeared in both domains but was inaccessible from either. We had to
> manually set the IP, gateway, and DNS.
>
> Can anyone give me any advice on how we can handle this problem?
>
> Thanks,
> - Steve

How is DNS configured between both companies?

Are both networks on the same subnet now, or are the offices using a VPN to
connect? Based on your post, it would appear that they are on the same
subnet/

One suggestion:
If you are assimilating the company, and both systems (yours and theirs) are
on the same subnet (assumption based on the description in your post), the
first thing is to coexist DNS by creating Secondary zones of the other on
yours, and vice versa.
Then settle on ONE DHCP server, namely yours, the Windows DHCP service.
Stick to your DNS servers. The secondaries zones on your DNS server have
references to the Master zones on the other system's DNS, so when an update
comes in from one of their machine through your DHCP, based on the Primary
DNS Suffix, it will attempt to register into their DNS zone, and the
secondary will send it up to the Master, on THEIR DNS server.
So there is nothing to worry about their systems properly still registering
in to their DNS Of course, make sure you have enough IPs to accomodate all
machines.

I hope that helps.

--
Ace

This posting is provided "AS-IS" with no warranties or guarantees and
confers no rights.

Ace Fekay, MCSE 2003 & 2000, MCSA 2003 & 2000, MCSA Messaging, MCT
Microsoft Certified Trainer


For urgent issues, you may want to contact Microsoft PSS directly. Please
check http://support.microsoft.com for regional support phone numbers.

Hi all,

Thanks for the responses!

Actually the networks are on different subnets. I am routing between all
the subnets and everything is on private lines so there are no VPNs.

Also, our DHCP server is the Cisco one. "Their" DHCP server is the Active
Directory one.

Marcin - thanks for the GPO suggestion and link. Definitely a possibility.

Ace - we already have the secondary DNS zones set up as you describe; this
was done when we created the trusts between the domains. If I understand you
correctly, you are suggesting that we only use our DNS servers in *both* DHCP
configs and let DNS sort it out. Is that right? That would be simple, and
elegant.

Thanks,
- Steve


"Ace Fekay [Microsoft Certified Trainer]" wrote:

> In news:2DA76775-52A8-4C74-9D0B-,
> Steve Kadish <>, posted the following:
> > Hi all,
> >
> > We recently merged with another company and we are trying to merge
> > their users and computers into our forest. So far the testing has
> > mostly gone smoothly, but I had one problem with my test of migrating
> > a workstation.
> >
> > The source domain uses Active Directory DHCP. The target domain uses
> > a DHCP server on a Cisco router. When I migrated the computer, it
> > continued to get a DHCP address from the source domain's DC, along
> > with the source domain's DNS servers. Therefore it didn't register
> > itself properly with the target domain's DNS servers; the workstation
> > appeared in both domains but was inaccessible from either. We had to
> > manually set the IP, gateway, and DNS.
> >
> > Can anyone give me any advice on how we can handle this problem?
> >
> > Thanks,
> > - Steve
>
> How is DNS configured between both companies?
>
> Are both networks on the same subnet now, or are the offices using a VPN to
> connect? Based on your post, it would appear that they are on the same
> subnet/
>
> One suggestion:
> If you are assimilating the company, and both systems (yours and theirs) are
> on the same subnet (assumption based on the description in your post), the
> first thing is to coexist DNS by creating Secondary zones of the other on
> yours, and vice versa.
> Then settle on ONE DHCP server, namely yours, the Windows DHCP service.
> Stick to your DNS servers. The secondaries zones on your DNS server have
> references to the Master zones on the other system's DNS, so when an update
> comes in from one of their machine through your DHCP, based on the Primary
> DNS Suffix, it will attempt to register into their DNS zone, and the
> secondary will send it up to the Master, on THEIR DNS server.
> So there is nothing to worry about their systems properly still registering
> in to their DNS Of course, make sure you have enough IPs to accomodate all
> machines.
>
> I hope that helps.
>
> --
> Ace
>
> This posting is provided "AS-IS" with no warranties or guarantees and
> confers no rights.
>
> Ace Fekay, MCSE 2003 & 2000, MCSA 2003 & 2000, MCSA Messaging, MCT
> Microsoft Certified Trainer
>
>
> For urgent issues, you may want to contact Microsoft PSS directly. Please
> check http://support.microsoft.com for regional support phone numbers.
>
>

In news:F766CBCB-C0A6-44F7-AA0B-,
Steve Kadish <>, posted the following:
> Hi all,
>
> Thanks for the responses!
>
> Actually the networks are on different subnets. I am routing between
> all the subnets and everything is on private lines so there are no
> VPNs.
>
> Also, our DHCP server is the Cisco one. "Their" DHCP server is the
> Active Directory one.
>
> Marcin - thanks for the GPO suggestion and link. Definitely a
> possibility.
>
> Ace - we already have the secondary DNS zones set up as you describe;
> this was done when we created the trusts between the domains. If I
> understand you correctly, you are suggesting that we only use our DNS
> servers in *both* DHCP configs and let DNS sort it out. Is that
> right? That would be simple, and elegant.
>
> Thanks,
> - Steve

Simple and elogant, yes, and if you are routed, that will work. VPN or
routed, same thing, you are connected. As for which machine gets an IP from
a DHCP server, the ones on their subnet is getting their config from their
DNS, and your subnet from your router. So I do not see how they are getting
an IP from your router or your machines are getting from their DHCP unless
of course the Cisco router is interconnecting and you have a DHCP scope set
for both subnets on the router. If that is the case, I would suggest to
disable the other scope otherwise it is a conflict of DHCP services on the
same subnet.

Since you are assimilating THEM, I would suggest to move away from Cisco
DHCP and use your own DC as the DHCP server. And I highly suggest to use
WINS on both sides. Configure a WINS server on one of your servers, probably
the same DC you confgure DHCP on. Then configure the following options on
your server. Add the WINS options on THEIR DHCP server for YOUR WINS server:
Also use YOUR DNS server instead of theirs on their side. This is the first
step to pointing everything on your end.

003 Router address
006 Internal DNS address
015 Internal AD DNS domain name
044 Wins Address
046 WINS Mode - 0x8

This way all resolution is on your end instead of theirs. It consolidates it
and centralizes it, and makes it easier towards the final switch over.

Ace

"Ace Fekay [Microsoft Certified Trainer]" wrote:

> Simple and elogant, yes, and if you are routed, that will work. VPN or
> routed, same thing, you are connected. As for which machine gets an IP from
> a DHCP server, the ones on their subnet is getting their config from their
> DNS, and your subnet from your router. So I do not see how they are getting
> an IP from your router or your machines are getting from their DHCP unless
> of course the Cisco router is interconnecting and you have a DHCP scope set
> for both subnets on the router. If that is the case, I would suggest to
> disable the other scope otherwise it is a conflict of DHCP services on the
> same subnet.
>
> Since you are assimilating THEM, I would suggest to move away from Cisco
> DHCP and use your own DC as the DHCP server. And I highly suggest to use
> WINS on both sides. Configure a WINS server on one of your servers, probably
> the same DC you confgure DHCP on. Then configure the following options on
> your server. Add the WINS options on THEIR DHCP server for YOUR WINS server:
> Also use YOUR DNS server instead of theirs on their side. This is the first
> step to pointing everything on your end.
>
> 003 Router address
> 006 Internal DNS address
> 015 Internal AD DNS domain name
> 044 Wins Address
> 046 WINS Mode - 0x8
>
> This way all resolution is on your end instead of theirs. It consolidates it
> and centralizes it, and makes it easier towards the final switch over.
>
> Ace
>
>
Hi Ace,

Unfortunately, moving from Cisco DHCP to Microsoft DHCP is not trivial,
because we have 14 locations and each has a Cisco router with a DHCP pool on
it. However, IP addressing is not the problem. Their computers are getting
IPs from their DHCP server, and ours from our server, as it should be. The
only problem is with the DNS registration.

It seems to me that I can set up WINS as you suggest event with the Cisco
DHCP. My only question is about option 15 - the DNS domain name. Let's call
our domain "parentco.com" and their domain "childco.com." Right now their
unmigrated workstations are "computer1.childco.com." If I set the WINS
option 15 to "parentco.com" on their WINS server, which is what I think you
are suggesting, won't all of their workstations become
"computer1.parentco.com" and become a problem?

Thanks,
- Steve

In news:36B4B961-D01F-4972-92C3-,
R. Steven Kadish <>, posted the
following:

> Hi Ace,
>
> Unfortunately, moving from Cisco DHCP to Microsoft DHCP is not
> trivial, because we have 14 locations and each has a Cisco router
> with a DHCP pool on it. However, IP addressing is not the problem.
> Their computers are getting IPs from their DHCP server, and ours from
> our server, as it should be. The only problem is with the DNS
> registration.
>
> It seems to me that I can set up WINS as you suggest event with the
> Cisco DHCP. My only question is about option 15 - the DNS domain
> name. Let's call our domain "parentco.com" and their domain
> "childco.com." Right now their unmigrated workstations are
> "computer1.childco.com." If I set the WINS option 15 to
> "parentco.com" on their WINS server, which is what I think you are
> suggesting, won't all of their workstations become
> "computer1.parentco.com" and become a problem?
>
> Thanks,
> - Steve

Good point about the 015, so we'll keep that out. As for DNS, you can
consolidate it to your DNS servers by changing their DHCP 006 options to
point to your DNS. Registration works based on the machine's Primary DNS
Suffix. When a machine registers, even into a DNS server that has a
secondary zone, say their machines are sending the registration to your
machine, the MNAME is queried and the registration request is sent to their
DNS server, then the secondary zone transfers and updates on to your
machine. So it is ok to have a secondary of their zone and the reg requests
go to them. As for their DCs, they can still point to themselves, and still
be able to resolve their own and your domain (because of them having a
secondary of your zone).

As for WINS, WINS does not use the suffixes, as you are implying. The
Primary DNS suffix defines the machine's domain, and the search suffix
defines what suffix the client side hostname resolver uses when devolving
single names. This means that on a machine that has a parentco.com suffix,
and you ping 'machinename,' the client side resolver will append
parentco.com to the name resulting in machinename.parentco.com, and then
uses that to ping. You can facilitate resolution for both sides by adding
the suffix of the other domain to each others' machines.

WINS is simply NetBIOS name resolution to IP. This facilitates any NetBIOS
based apps and services that require NetBIOS name resolution, and do NOT use
suffixes. NetBIOS broadcasts are restricted across routers, and such apps
and services will fail when trying to communicate across a router.. Some
apps and serivice examples that use NetBIOS: browser service (network
neighborhood), printer browsing, certain functions of Outlook's calendaring
availability publishing, SQL, and many others.

I hope that makes sense.

Ace

Hi Ace,

Thanks for your continued help. I started implementing your suggestions and
was successful up to a point. Here's what I did:

- installed a WINS server in the target domain (parentco.com)
- configured the DHCP server in the source domain (childco.com) with the 06,
044, and 046 options. The workstations in the source domain are now using
the DNS servers and WINS server in the target domain.

Then I migrated a computer from the childco.com to parentco.com. Everything
was successful. I could connect to the computer's ADMIN$ share remotely,
etc. So far, so good. This was further than I had gotten before.

However, the migrated computer STILL did not register itself in the target
domain's DNS automatically. I could resolve computer74.childco.com (the
original A record), but not computer74.parentco.com.

I ran "ipconfig /registerdns" on the migrated computer, and then it
registered itself in parentco's DNS. Now I have A records for BOTH
computer74.childco.com and computer74.parentco.com.

Shouldn't this DNS registration be happening automatically?

Thanks much,
- Steve


"Ace Fekay [Microsoft Certified Trainer]" wrote:

> In news:36B4B961-D01F-4972-92C3-,
> R. Steven Kadish <>, posted the
> following:
>
> > Hi Ace,
> >
> > Unfortunately, moving from Cisco DHCP to Microsoft DHCP is not
> > trivial, because we have 14 locations and each has a Cisco router
> > with a DHCP pool on it. However, IP addressing is not the problem.
> > Their computers are getting IPs from their DHCP server, and ours from
> > our server, as it should be. The only problem is with the DNS
> > registration.
> >
> > It seems to me that I can set up WINS as you suggest event with the
> > Cisco DHCP. My only question is about option 15 - the DNS domain
> > name. Let's call our domain "parentco.com" and their domain
> > "childco.com." Right now their unmigrated workstations are
> > "computer1.childco.com." If I set the WINS option 15 to
> > "parentco.com" on their WINS server, which is what I think you are
> > suggesting, won't all of their workstations become
> > "computer1.parentco.com" and become a problem?
> >
> > Thanks,
> > - Steve
>
> Good point about the 015, so we'll keep that out. As for DNS, you can
> consolidate it to your DNS servers by changing their DHCP 006 options to
> point to your DNS. Registration works based on the machine's Primary DNS
> Suffix. When a machine registers, even into a DNS server that has a
> secondary zone, say their machines are sending the registration to your
> machine, the MNAME is queried and the registration request is sent to their
> DNS server, then the secondary zone transfers and updates on to your
> machine. So it is ok to have a secondary of their zone and the reg requests
> go to them. As for their DCs, they can still point to themselves, and still
> be able to resolve their own and your domain (because of them having a
> secondary of your zone).
>
> As for WINS, WINS does not use the suffixes, as you are implying. The
> Primary DNS suffix defines the machine's domain, and the search suffix
> defines what suffix the client side hostname resolver uses when devolving
> single names. This means that on a machine that has a parentco.com suffix,
> and you ping 'machinename,' the client side resolver will append
> parentco.com to the name resulting in machinename.parentco.com, and then
> uses that to ping. You can facilitate resolution for both sides by adding
> the suffix of the other domain to each others' machines.
>
> WINS is simply NetBIOS name resolution to IP. This facilitates any NetBIOS
> based apps and services that require NetBIOS name resolution, and do NOT use
> suffixes. NetBIOS broadcasts are restricted across routers, and such apps
> and services will fail when trying to communicate across a router.. Some
> apps and serivice examples that use NetBIOS: browser service (network
> neighborhood), printer browsing, certain functions of Outlook's calendaring
> availability publishing, SQL, and many others.
>
> I hope that makes sense.
>
> Ace
>
>

In news:96A0C610-D158-4ECE-93A8-,
Steve Kadish <>, posted the following:
> Hi Ace,
>
> Thanks for your continued help. I started implementing your
> suggestions and was successful up to a point. Here's what I did:
>
> - installed a WINS server in the target domain (parentco.com)
> - configured the DHCP server in the source domain (childco.com) with
> the 06, 044, and 046 options. The workstations in the source domain
> are now using the DNS servers and WINS server in the target domain.
>
> Then I migrated a computer from the childco.com to parentco.com.
> Everything was successful. I could connect to the computer's ADMIN$
> share remotely, etc. So far, so good. This was further than I had
> gotten before.
>
> However, the migrated computer STILL did not register itself in the
> target domain's DNS automatically. I could resolve
> computer74.childco.com (the original A record), but not
> computer74.parentco.com.
>
> I ran "ipconfig /registerdns" on the migrated computer, and then it
> registered itself in parentco's DNS. Now I have A records for BOTH
> computer74.childco.com and computer74.parentco.com.
>
> Shouldn't this DNS registration be happening automatically?
>
> Thanks much,
> - Steve
>> Ace

Yes, it should have registered. What DNS servers is the DHCP server at the
source domain using? You would want it to use the target's. Give that a
shot.

No problem for the help!!

Ace