Late in the middle of the night one of the domain controllers in the same AD site as the Exchange servers stopped functioning (TBD why) and the Exchange servers continued to try using that particular DC\/GC to perform lookups.<\/p>\n
The DC wasn’t accessible via most means and the event logs in the CAS servers had a few items that were descriptive, but not terribly helpful:
\n___<\/p>\n
Event Type: Warning
\nEvent Source: MSExchange ADAccess
\nEvent Category: Topology
\nEvent ID: 2116
\nDate: 2\/13\/2009
\nTime: 3:24:40 AM
\nUser: N\/A
\nComputer: HUB\/CAS_server
\nDescription:
\nProcess IISIPM72AE0B7E-9F63-4D30-80F3-A58AB1DEDB01 -AP “MSEXCHANGEOWAAPPPOOL (PID=6904). The domain controller DC.domain.local is running Windows (Unknown Operating System) (Unknown Service Pack). Exchange Active Directory Provider requires that domain controllers are running Windows Server 2003 Service Pack 1 or later versions of Windows.
\n___<\/p>\n
So of all the questions I need to ask M$ this morning is why didn’t Exchange start using the other 3 domain controllers we had available? They were in fact out of site, but functioning perfectly fine. During the AD Topology discovery immediately after the 2116 Event was the standard AD Topology event, but it indicated that the DC’s OS being unknown is NOT enough for Exchange to want to switch to doing lookups on another GC. Pity.
\n___
\nEvent Type: Information
\nEvent Source: MSExchange ADAccess
\nEvent Category: Topology
\nEvent ID: 2080
\nDate: 2\/13\/2009
\nTime: 3:24:44 AM
\nUser: N\/A
\nComputer: HUB\/CAS_servers
\nDescription:
\nProcess IISIPM72AE0B7E-9F63-4D30-80F3-A58AB1DEDB01 -AP “MSEXCHANGEOWAAPPPOOL (PID=6904). Exchange Active Directory Provider has discovered the following servers with the following characteristics:
\n (Server name | Roles | Enabled | Reachability | Synchronized | GC capable | PDC | SACL right | Critical Data | Netlogon | OS Version)
\nIn-site:
\nDomain.ad.local1 CDG 1 7 7 1 0 0 0 7 0
\nDomain.external.com1 CDG 1 7 7 1 0 1 1 7 1
\n Out-of-site:
\nDomain.ad.local2 CDG 1 7 7 1 0 1 1 7 1
\nDomain.ad.local3 CDG 1 7 7 1 0 1 1 7 1
\nDomain.external.com2 CDG 1 7 7 1 0 1 1 7 1
\nDomain.external.com2 CDG 1 7 7 1 0 1 1 7 1
\nDomain.ad.local4 CDG 1 7 7 1 0 1 1 7 1
\nDomain.external.com24 CDG 1 7 7 1 0 1 1 7 1
\n___<\/p>\n","protected":false},"excerpt":{"rendered":"
Late in the middle of the night one of the domain controllers in the same AD site as the Exchange servers stopped functioning (TBD why) and the Exchange servers continued to try using that particular DC\/GC to perform lookups. The DC wasn’t accessible via most means and the event logs in the CAS servers had …<\/p>\n","protected":false},"author":12,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[10],"tags":[],"class_list":["post-129","post","type-post","status-publish","format-standard","hentry","category-tech"],"_links":{"self":[{"href":"https:\/\/www.briandeyo.us\/index.php\/wp-json\/wp\/v2\/posts\/129","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.briandeyo.us\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.briandeyo.us\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.briandeyo.us\/index.php\/wp-json\/wp\/v2\/users\/12"}],"replies":[{"embeddable":true,"href":"https:\/\/www.briandeyo.us\/index.php\/wp-json\/wp\/v2\/comments?post=129"}],"version-history":[{"count":1,"href":"https:\/\/www.briandeyo.us\/index.php\/wp-json\/wp\/v2\/posts\/129\/revisions"}],"predecessor-version":[{"id":130,"href":"https:\/\/www.briandeyo.us\/index.php\/wp-json\/wp\/v2\/posts\/129\/revisions\/130"}],"wp:attachment":[{"href":"https:\/\/www.briandeyo.us\/index.php\/wp-json\/wp\/v2\/media?parent=129"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.briandeyo.us\/index.php\/wp-json\/wp\/v2\/categories?post=129"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.briandeyo.us\/index.php\/wp-json\/wp\/v2\/tags?post=129"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}