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Richard Beier
Asked: 2009-06-04 10:16:43 +0800 CST

Can't log in using second domain controller when first DC is unreachable

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We're a small web development company. Our domain has two DCs: a main one (BEEHIVE, 192.168.3.20) in the datacenter and a second one (SPHERE2, 10.0.66.19) in the office. The office is connected to the datacenter via a VPN.

We recently had a brief network outage in the office. During this outage, we weren't able to access the domain from our office machines. I had hoped that they would fail over to the DC in the office, but that didn't happen. So I'm trying to figure out why. I'm not an expert on Active Directory so maybe I'm missing something obvious.

Both domain controllers are running a DNS server. Each office workstation is configured to use the datacenter DC as its primary DNS server, and the office DC as its secondary:

  DNS Servers . . . . . . . . . . . : 192.168.3.20
                                      10.0.66.19


Both DNS servers are working, and both domain controllers are working (at least, I can connect to them both using AD Users + Computers).

Here are the SRV records that point to the domain controllers (I've changed the domain name but I've left the rest alone):

C:\>nslookup
Default Server:  beehive.ourcorp.com
Address:  192.168.3.20

> set type=srv
> _ldap._tcp.ourcorp.com
Server:  beehive.ourcorp.com
Address:  192.168.3.20

_ldap._tcp.ourcorp.com  SRV service location:
          priority       = 0
          weight         = 100
          port           = 389
          svr hostname   = beehive.ourcorp.com
_ldap._tcp.ourcorp.com  SRV service location:
          priority       = 0
          weight         = 100
          port           = 389
          svr hostname   = sphere2.ourcorp.com
beehive.ourcorp.com     internet address = 192.168.3.20
sphere2.ourcorp.com     internet address = 10.0.66.19

Does anyone have any ideas?


Thanks,
Richard

windows domain-name-system active-directory

2 Answers

  1. Best Answer

    Check to make sure that BOTH are Global Catalogs.

    Howto:

    1.) Open Active Directory Sites and Services.

2.) Scroll down, expand the site that your DC's are in. Expand
`Servers'.

3.) Expand each of your DC's so that they're showing `NTDS Settings'.

4.) Right-click on 'NTDS Settings', select `Properties'.

5.) Ensure that the `Global Catalog' checkbox on each is checked.

    DISCLAIMER:

    I'm assuming that you've already checked your replication, made sure everything else is working properly, etc. This is intended to be a quick-check option.

    • 8

  2. My wild guess is your site boundaries are wrong.

    • 1