I'm in the process of migrating from Exchange 2010 to 2013. Everything is going as planned so far except every 20 minutes I get the following event log error on the Exchange 2013 server. I've changed the names but the environment is as follows:

EX2013A = Exchange 2013

EX2010A = Exchange 2010

All virtual directories, autodiscover, etc. use the fqdn of companymail.domain.com.

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Log Name:      Application
Source:        MSExchange Front End HTTP Proxy
Date:          8/3/2015 4:21:28 PM
Event ID:      3005
Task Category: Core
Level:         Warning
Computer:      EX2013A.domain.com
Description:
[Autodiscover] Marking ClientAccess 2010 server EX2010A.domain.com (https://ex2010a.domain.com/Autodiscover) as unhealthy due to exception: System.Net.WebException: The remote name could not be resolved: 'mail.domain.com'
   at System.Net.HttpWebRequest.GetResponse()
   at Microsoft.Exchange.HttpProxy.ProtocolPingStrategyBase.Ping(Uri url)

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As you can see for some reason it is trying to resolve mail.domain.com instead of companymail.domain.com. I've check all the usual places (virtual directories, autodiscover, etc.) but they are all using the fqdn of companymail.domain.com.

Tho

This might be dumb question but did you check autodiscover service internal uri on the CAS server?

Get-ClientAccessServer | select name, autodiscoverserviceinternaluri

AutoDiscoverServiceInternalUri on both new EX2013 servers are set to https://autodiscover.domain.com/Autodiscover/Autodiscover.xml

Hi,

Based on my knowledge, we are getting these events because Exchange 2013 does monitor the health status of the Legacy servers, in your case for Exchange 2010. But at the same time it does not have separate specific monitoring parameters. So basically it looks up for the virtual directory on Exchange 2010 Server and it does not find there and it throws up the warning. These virtual directories were introduced from exchange 2010.

As these events are for the directories of Exchange 2010 which do not exist and has no configuration impact, you can safely ignore these events.

Best Regards.

 

But the autodiscover directory does exist in Exchange 2010. mail.domain.com however is not configured anywhere (I'm using companymail.domain.com) yet the autodiscover service on Exchange 2013 is trying to resolve it; hence the "The remote name could not be resolved: 'mail.domain.com'" error.