Windows 2012 2008 DNS


Here my configuration
3 DCs servers

Server1, Windows 2012 R2, DNS, DHCP, DC with 4 FSMO roles
Server2, Windows 2008 R2, DNS, DC
Server3, Windows 2008 R2, DNS, DC

IP config of the 3 servers is as follow :
Server1 : DNS1 = Server1, DNS2 = Server2
Server2 : DNS1 = Server2, DNS2 = Server3
Server3 : DNS1 = Server3, DNS2 = Server1

Sometimes it happens that for internal reasons we have to shut down all 3 servers for many hours.
My problem is that I do have problem for restarting DNS on servers when turning them on.

The DNS Service starts OK but DNS configuration is not retreaved and it asks me to to create a new DNS server of something like that

My questions :
Is my DNS IP configuration correct ?

When all 3 servers have been shut down, Is there « an order » to turn on servers, one after the other, or all 3 at the same time ?

Is there a way to retreive DNS config and not playing with IP DNS addressing  ?

Thank you
Who is Participating?
David Johnson, CD, MVPOwnerCommented:
server 1 when up and running server2 and 3 at the same time. are 2 and 3 also GC's?  I've never seen this problem
Server1 : DNS1 = Server2, DNS2 = Server3, DNS3 = Server1
Server2 : DNS1 = Server1, DNS2 = Server3, DNS3 = Server2
Server3 : DNS1 = Server1, DNS2 = Server2, DNS3 = Server3

Unless you have a single DC, servers should point to alternate DNS server before pointing to themselves.

Some IT people may use as DNS3, personally I never use that.
gadsadAuthor Commented:
All servers are GC

I though as a general rule all DC servers should first point to themselves before pointing to alternate DC

KTACZALA what you are saying it new to me, are you sure of that? that is Microsoft recommendation?

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There are differing opinions, but this is the way I've always done it.
if you do a search for which DNS server first, read several.
@ktaczala - Even with Microsoft, are there differences of opinion:

 From the Active Directory team at Microsoft:

It depends on who you ask. :-) We in MS have been arguing this amongst ourselves for 11 years now. Here are the general guidelines that the Microsoft AD and Networking Support teams give to customers, based on our not inconsiderable experience with customers and their CritSits:
1.If a DC is hosting DNS, it should point to itself at least somewhere in the client list of DNS servers.
2.If at all possible on a DC, client DNS should point to another DNS server as primary and itself as secondary or tertiary. It should not point to self as primary due to various DNS islanding and performance issues that can occur. (This is where the arguments usually start)
3.When referencing a DNS server on itself, a DNS client should always use a loopback address and not a real IP address.
4.Unless there is a valid reason not to that you can concretely explain with more pros than cons, all DC’s in a domain should be running DNS and hosting at least their own DNS zone; all DC’s in the forest should be hosting the _MSDCS zones. This is default when DNS is configured on a new Win2003 or later forest’s DC’s. (Lots more arguments here).
5.DC’s should have at least two DNS client entries.
6.Clients should have these DNS servers specified via DHCP or by deploying via group policy/group policy preferences, to avoid admin errors; both of those scenarios allow you to align your clients with subnets, and therefore specific DNS servers. Having all the clients & members point to the same one or two DNS servers will eventually lead to an outage and a conversation with us and your manager. If every DC is a DNS server, clients can be fine-tuned to keep their traffic as local as possible and DNS will be highly available with special work or maintenance. It also means that branch offices can survive WAN outages and keep working, if they have local DC’s running DNS.
7.We don’t care if you use Windows or 3rd party DNS. It’s no skin off our nose: you already paid us for the DC’s and we certainly don’t need you to buy DNS-only Windows servers. But we won’t be able to assist you with your BIND server, and their free product’s support is not free.
8.(Other things I didn’t say that are people’s pet peeves, leading to even more arguments).

There are plans afoot to consolidate all this info, expand it, and get our message consistent and consolidated. This has started in the Windows Server 2008 R2 BPA for DNS. We also recently released a new namespace planning site that explains and prevents some design pitfalls:

DNS Namespace Planning Solution Center

And we offer this great guide and portal site:

Creating a DNS Infrastructure Design

DNS Portal

Cliff GaliherCommented:
If you are shutting down all three servers simultaneously, you will always have a delay bringing the first one back up. Not just because of DNS. It will try to contact other DCs to see if any changes have occurred and when none reply, it will not consider itself valid. Because it is not valid, no AD integrated DNS zones will be available either. It will wait until other DCs are up, and they compare replication states.
gadsadAuthor Commented:
I have noticed at several occasions (at different customers and with different configurations)  that when shutting down all DCs (all GC and DNS) simultaneously DNS do not start properly. And I have to play around with IP configuration and stop/start DNS service to make it start properly. Maybe there is a delay for all DCs to recognize each other, and I am not patient enough, maybe it is normal.
What is not normal is a shutdown of all DC's...  Could I inquire as to the reason for this?

gadsadAuthor Commented:
Ther electicity  company informed us that there will be a power shutdown for 12 hours. No choice but to shutdown all DCs
David Johnson, CD, MVPOwnerCommented:
a shutdown and a power on after 12 hours will not affect your dns.. I've had virtual machines powered down for days with no dns errors.
Firstly, there is no right or wrong answer on which DNS to point multiple DCs at, regardless of what some people suggest. it all depends on your circumstances and what you are trying to achieve.

I don't think anyone would dispute the idea that having all DNS servers listed on a DC is a good idea, so I recommend adding a 3rd DNS server to each of your DCs.

What is disputed is the order in which to list them.
as its rare all the DCs are down at once having DCs listing each other is normally fine and has some performance advantages.
It does however have 2 relevant disadvantages:
If all servers go down, it causes issues when starting back up as DNS resolutions may fail during AD startup
if 2 of the 3 servers go down, it can cause a small delay for some tasks due to timeouts, but usually works ok in the end.

if the power down of all servers is a rare occurrence it's probably not worth worrying about it too much.
If it something you need to plan for, set ONE of the DCs to use itself as primary DNS (actual IP, NOT loopback) and make sure that DC is set to start up before the other 2.
gadsadAuthor Commented:
Hello TotallyTonto

Are you suggesting something like that?

In case all 3 servers will be down Server1 will be started up before the other 2

Server1: DNS1 = server1, DNS2= Server2, DNS3 = Server3
Server2: DNS1= Server1, DNS2= Server3, DNS3= Server2
Server3: DNS1 = Server1, DNS2= Server2, DNS3= Server3

it's not ideal but yea, that would be fine for your circumstances. It could cause minor delays if server 1 went down and the other 2 were running but probably covers your options reasonably well.
you could make server 3 see server 2 if you'd like, as long as you make sure server 2 is set to come on before server 3?
gadsadAuthor Commented:
Do you have a better suggestion?
Not in your case, no. There are plenty of experts that will agree and disagree with what I've suggested, but I can't think of another option that would meet your specific requirements.

It's all about compromise between what you want and what you can actually achieve.
gadsadAuthor Commented:
thanks to all
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