Users not able to authenticate to second domain controller

[windowsfan]

I have two domains in my network. domain 1 has all 5 roles and both DC's are GC. When DC1 as down due to hardware failure no one was able to authenticate to dc2 , what could be wrong? how can I check?

 

[pagy]

I assume you mean you have 2 domain controllers and not 2 domains

Sounds like a DNS issue, are boths domain controllers running DNS, if so the clients should have both set in their dns settings, dc1 as the preferred and dc2 as the alternate

Paul
MCSE


"Two things are infinite: the universe and human stupidity; and I'm not sure about the the universe."
Albert Einstein

 

[windowsfan]

Yes I meant two DCs and not two domain.
what I configure user with only one DNS, why it will not authenticate to second DC's?

 

[pagy]

If you configure your clients preferred dns with only dc1 IP address and dc1 is offline how is the dc locator mechanism in XP supposed to find a domain controller to authenticate to....


How Domain Controllers Are Located in Windows XP

http://support.microsoft.com/kb/314861

Paul
MCSE


"Two things are infinite: the universe and human stupidity; and I'm not sure about the the universe."
Albert Einstein

 

[windowsfan]

second DC has 2 NIC. it's acting as router. on second NIC I have unchecked the option [register dns].

 

[pagy]

huh???? The dns settings on your client PCs is what I'm referring to

Paul
MCSE


"Two things are infinite: the universe and human stupidity; and I'm not sure about the the universe."
Albert Einstein

 

[windowsfan]

hi Paul,
Users PC is only configured with one dns (ip Of dc1). with this configuration why it will not authenticate to dc2.

 

[pagy]

yeah that's it. i am of course assuming that dc2 is running dns on it.

so on your user pc preferred dns should be dc1 and alternate dns should be set to dc2 ip address.

Paul
MCSE


"Two things are infinite: the universe and human stupidity; and I'm not sure about the the universe."
Albert Einstein

 

[windowsfan]

what if dc1 and dc2 both are up and running and primary dns is set to ip of dc1 and nothing for secondary dns.
will any user with the above configuration able to authenticate to dc2, if not why?

 

[scottew]

It won't because you have not entered the secondary DNS information. The client PC has no idea how to find DC2 in order to authenticate.

Scott

 

[Davetoo]

DNS is not a broadcast like DHCP, you have to direct your client machines to the DNS server. So, if you tell them, via DHCP, that there are two DNS servers and one is down, then they'll automatically look for the 2nd one.

I'm Certifiable, not cert-ified.
It just means my answers are from experience, not a book.

 

[bracadar]

Let's kick that dead "DNS" horse ONE more time!!!

 

[windowsfan]

so if I configure all users with DNS1 and DNS2, will all users authenticate to DC1 for authentication as long as it's up and running?
How is load balancing done between ADs for authenticaiton?

"It won't because you have not entered the secondary DNS information. The client PC has no idea how to find DC2 in order to authenticate."
isn't DC1 aware that there is a DC2 which is GC?

Thanks for everyone's input.

 

[58sniper]

That depends on how your sites and services, as well as subnets are setup.

Pat Richard
Microsoft Exchange MVP

 

[windowsfan]

both DC's are in same site and subnet.

 

[58sniper]

If that's the case, and DNS is set to two different DCs, then as long as there's a GC available when one DC goes down, they should be able to authenticate to the other DC.

Pat Richard
Microsoft Exchange MVP