[Samba] Moving the 1st DC (FSMO) to another site - howto?

Ole Traupe ole.traupe at tu-berlin.de
Thu Jun 23 15:21:26 UTC 2016

James, it took me a while, but now I am doing this. I created the new 
site with RSAT (want to move over my 1st DC), but this new site isn't 
showing in the DNS console. Do I have to create the new site there, as well?


On 25.04.2016 14:27, lingpanda101 at gmail.com wrote:
> On 4/22/2016 3:43 PM, Ole Traupe wrote:
>> Hi Mathias, lingpanda101, thank you for the quick reply! Comments 
>> inline.
>> On 22.04.2016 15:14, mathias dufresne wrote:
>>> Hi Ole,
>>> A - If I read correctly you have only one DC and you want to move 
>>> from one network to another.
>>> To achieve that change you will have to change all A/AAAA records in 
>>> your both AD zones (root zone and _msdcs zone).
>>> Once that is done you will have to change resolver configuration on 
>>> your clients for they can send DNS request to the new IP.
>>> Can't see anything else. Nothing about AD site: AD sites are linked 
>>> to clients networks and clients networks do not change, only DC 
>>> network is changing.
>>> B - If I don't read correctly, you have several DC. Move on DC to 
>>> the new network, change A and AAAA records related to that DC to 
>>> reflect the network change.
>>> If you move one DC not used by clients as DNS server, no change on 
>>> client side.
>> I have two DCs. The one with the FSMO roles is on the physical server 
>> to move. Unfortunately I don't have another host for this VM staying 
>> at the old place.
>> Also, I will have a few clients at the new place soon, so I think a 
>> second site is the way to go? Sorry, I mentioned this only implicitly 
>> in "moving our lab". Is it possible to just transfer an existing DC 
>> to another site? By manually recreating all the records?
>> The moving DC will definitely be used as first DNS server, as the 
>> second DC is on very old, potentially unreliable hardware. But 
>> changing the DNS server config on the clients is no big deal.
>> In response to the message from lingpanda101:
>> I was not talking about transferring the FSMO roles. Sorry if I had 
>> been unclear about that.
>> In theory, I will have access to both networks from both places. In 
>> practice, the firewall settings initially are very restrictive. So I 
>> try not to forget anything in preparation. I have thought of...
>> - all the ports samba regularly uses (including DNS requests)
>> - rsync ports for sysvol replication
>> - ...
>> I would be very happy about the steps to create a new site and to 
>> transfer DC and some client records to it!
>> Probably I will see for the file server integration first, while 
>> using the 2nd DC as fallback for DNS and logon. Once that works I 
>> deal with bringing the 1st DC back into the game.
>>> C - You are lazy and you have enough physical computer to play with.
>> Yes and no. ;)
>>> Just create a new DC on the new site, join it to the domain.
>>> If then you want to remove old DC you will have to seize (or 
>>> transfer if it works) FSMO roles, change DNS configuration on client 
>>> side, but as that's a new DC you don't have to modify A/AAAA records.
>>> IMPORTANT NOTE: with internal DNS you have only one SOA. SOA is 
>>> where DNS update goes. If you remove old SOA you must change SOA 
>>> record to assign it to a working DC. Without that no change in your 
>>> DNS zones will be possible for later use (DC moving from site to 
>>> site is the main point, auto-update pushed by DHCP or clients won't 
>>> work too).
>> I followed the recent/ongoing discussion on that. With "DNS updates" 
>> you mean the clients automatically updating their records, right? 
>> Because I am pretty sure that with internal DNS I can make changes to 
>> DNS structure with RSAT on 2nd DC and it gets replicated to the 1st 
>> DC (SOA). Maybe the only issue with internal DNS is that the 2nd, 3rd 
>> etc. DC won't advertise themselves as SOA, and so automatic updates 
>> fail when the 1st DC is offline.
>>> 2016-04-22 13:44 GMT+02:00 Ole Traupe <ole.traupe at tu-berlin.de 
>>> <mailto:ole.traupe at tu-berlin.de>>:
>>>     Hi List,
>>>     I'll probably have to move my FSMO role owner to another site.
>>>     Like at the end of next week (depends on tight transportation
>>>     schedules). So there is no actual time for testing anything, I am
>>>     afraid.
>>>     We are in the process of moving our lab, with our offices staying
>>>     in the old building for now (different class C subnets). The
>>>     physical machine is basically a file server (hosting DC1 as a VM)
>>>     which is particularly needed at the new site. Plus: Summer is
>>>     coming and the new site has cooling. Unfortunately, our university
>>>     techsup can't span a VLan to merge these two sites. So I am trying
>>>     to figure out how to do it. In earlier discussions on DC failover
>>>     strategies I was suggested to have my DCs on different sites (with
>>>     different subnets), so I figure it being possible in general.
>>>     The necessary steps likely include:
>>>     - modifying my current DNS config: create another site, move DC1
>>>     over, also the file server (AD member)
>>>     - update all the clients' 1st DNS server entries to reflect the
>>>     new IP of DC1 (and network share mappings)
>>>     - set some firewall rules allowing for logon and smb communication
>>>     etc.
>>>     Samba is version 4.2.5 with internal DNS.
>>>     Any advice, instructions, heads-up, warnings are very welcome!
>>>     Best regards,
>>>     Ole
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> Ole,
>     Will you be using Microsoft RSAT to create the sites? If so do 
> follow this guide
> http://blogs.technet.com/b/canitpro/archive/2015/03/04/step-by-step-setting-up-active-directory-sites-subnets-amp-site-links.aspx 
> Will you be changing your IP of the domain controller? If so follow 
> this guide.
> https://wiki.samba.org/index.php/Change_IP_address_of_an_Samba_AD_DC
> If using DHCP. Give your clients the DNS IP of your new site DC. That 
> should be it.

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