A common thing to do in a 'hub and spoke' network is to configure the
DCs in 'spoke' sites to NOT register domain-wide SRV records.  That way,
if the DC in a spoke site goes down, the client will discover
domain-wide SRV records for only DCs in the hub site.  This prevents the
client from authenticating to a DC in some other spoke site.  If the
hub-to-spoke links are relatively slow, this can make a big difference,
as it has to traverse only one slow link instead of two.
Dave

-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of joe
Sent: Tuesday, March 29, 2005 11:26 PM
To: [email protected]
Subject: RE: [ActiveDir] AD Site Confusion


Jorge keeps saying it in different ways and I think people are missing
the point...

The coverage of neighboring sites occurs when there is no DC in the
site, it doesn't occur when a site's DCs are down. This is all keyed off
of the site containers in the configuration. I have seen DCs being
promoed into a Domain in a site and the DCs from other sites
unregistering their records in that site before the DC is even promoed
up, all because the server object in the site already replicated around.


So as Jorge as said....

Look up local site DCs by DNS queries to Site based entries for the
domain. If none of those DCs are cool, ask for the global list of all
DCs for the domain and use one of those. It isn't the most efficient and
you will find odd things like clients in Florida hitting DCs in Seattle
when there is another DC in another city in Florida that would be better
to use. The idea seems to be if you can't use a DC in your site, screw
it, use any DC that responds. This is one of the reasons why Exchange
doesn't really use the standard mechanism for DC/GC service location.
They walk the metrics of the site connections trying to find the
closest.

  joe


 

-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Jorge de
Almeida Pinto
Sent: Tuesday, March 29, 2005 6:08 AM
To: [email protected]
Subject: RE: [ActiveDir] AD Site Confusion

Hi Neil,

Presuming the clients somehow have access to DNS (preferred or
alternate) they will first try to reach the DCs in their own site (site
A). As all DCs are down in site A the clients then will ask for all DCs
in the domain that have registered the domain specific DNS records.

For more info on this see:
* http://www.windowsitpro.com/Articles/Print.cfm?ArticleID=37935
Authentication Topology by Gil Kirkpatrick
* http://www.windowsitpro.com/Windows/Article/ArticleID/40718/40718.html
Designing for DC Failover by Sean Deuby 

Autositecoverage only works for DC-less sites. So yes, it behaves
differently for situation 1 (autositecoverage will occur) and 2 (no
autositecoverage will occur)

Cheers
Jorge

-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Ruston, Neil
Sent: dinsdag 29 maart 2005 11:56
To: '[email protected]'
Subject: RE: [ActiveDir] AD Site Confusion

Thanks Jorge.

Are you implying that the answer to the original question is therefore
'no'? This has huge ramifications in the branch office. Or did I simply
explain how the answer is 'yes', but for the wrong reasons??

Are you also saying that DCs (and sitecoverage) handle the following 2
scenarios in different ways: 1. No DCs installed in some site 2. DCs
installed in some site but non available

Can you expand on your previous post please?

Thanks,
neil


-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Jorge de
Almeida Pinto
Sent: 29 March 2005 10:21
To: [email protected]
Subject: RE: [ActiveDir] AD Site Confusion


I think that's incorrect if you're talking about autositecoverage.
Autositecoverage by DCs from some domain for some site will only occur
if some site has no DCs from that same domain. Although DCs are down and
not available, the DCs in other sites in the same domain see in their
own replica that that site has DCs and autositecoverage will occur.
Sitecoverage will occur by other DCs if you configured it manually
through the registry or a GPO

Cheers,
Jorge

-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Ruston, Neil
Sent: Tuesday, March 29, 2005 09:25
To: '[email protected]'
Subject: RE: [ActiveDir] AD Site Confusion

Depending upon your site links, DCs in either site B or C will advertise
themselves as available to site A. The DCs in the site with lowest cost
to site A will perform this role.

What do you mean by 'take down'? Are you taking a WAN link down or
powering off the DCs or demoting them or what?

neil


-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Matt Brown
Sent: 28 March 2005 21:55
To: [email protected]
Subject: [ActiveDir] AD Site Confusion


I have 3 sites, site A has 2 DC's and site B & C each have 1 DC.

When I take down site A (both DC's), the clients in Site A cannot log
in. Shouldn't they be able to log in using site B or C?

Thanks,
--
Matt Brown
Information Technology System Specialist Eastern Washington University



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