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date: Mon, 1 May 2006 14:16:01 -0700,
group: microsoft.public.exchange.clustering
back
Re: Clustered Backend Servers - HTTP Virtual Server
Wow, almost missed the reference to me in your reply Russ! I actually put up
a blog post several years that talks about host headers and clustering
(http://blogs.technet.com/evand/archive/2004/05/23/139965.aspx). Now, it's
interesting to note that the host headers are not really needed in many
cases (FE or BE), and they're not generally stamped in E2k3 servers like
they were on E2k.
So, as I understand the question - you have host headers on your FE server
and you want to know if you need to put them on the BE cluster HTTP protocol
VS as well. The answer is a resounding "maybe". So long as your FE or BE
HTTP protocol VS are UNIQUELY DISTINGUISHABLE from any other HTTP VS on that
same server by some other method (ie - by IP) then there's no reason to have
host headers. They're only used to further distinguish HTTP VS when there's
some question about the HTTP request going to the right place.
In the case of FE proxy behavior, the requests will be received by the FE
server and handled by an HTTP VS on the FE server. So long as your
"catch-all" HTTP VS (ie - the one with no host header specified) is the
correct HTTP VS for the task, there's no host header required. Only if the
"catchall" HTTP VS is *NOT* the right HTTP VS for the task (or if there is
no "catchall" HTTP VS) will you need host header on the FE.
Then, the FE repacks the request onto a port 80 proxied request back to the
proper BE server. I believe this is done to the FQDN of the EVS (so that it
gets to the proper BE server node). On that I'm not 100% sure, but that's
what I remember. In any event, this means that the BE server HTTP VS needs
to either be a "catchall" HTTP VS, or it needs to have the proper
FQDN-of-the-EVS set as the host header.
And, as I state in the blog posting... you don't need any host headers for
this ANYWHERE unless you're doing something special (like hosting multiple
namespaces with different settings on each, etc).
--
Evan Dodds
Program Manager
Microsoft Exchange Server
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This posting is provided "AS IS" with no warranties, and confers no rights.
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"Russ Kaufmann [MVP]" wrote in message
news:uIRsHvfbGHA.3380@TK2MSFTNGP04.phx.gbl...
> "Adoyt" wrote in message
> news:C0ABC896-05C1-476E-8CE4-F163E108EB05@microsoft.com...
>> http://www.microsoft.com/technet/prodtechnol/exchange/guides/E2k3TechRef/9299109d-4ee9-4647-8957-f580be9c3a55.mspx?mfr=true
>>
>> The link above suggests that the http virtural server be configured with
>> the
>> host header of the public webmail url (ie webmail.company.com) on
>> clustered
>> backend servers. Is this a best practice? I don't currently have this
>> in
>> place and don't have problems accessing my clustered backend servers
>> through
>> a frontend server.
>
> Rod and Simon have pretty much hit on the topic. However, I think your
> point of confusion is why these same host headers should be entered on the
> BE servers, too. What most people fail to realize is that the FEs work
> directly with the BEs and basically "proxy" the OWA requests and the OWA
> pages. Perhaps Evan can give a better explanation, but I think that helps
> understand the "why" in this case. So, because the FE can receive requests
> from a number of different clients potentially using host headers, it is
> important that any host headers that are added to the FEs are also added
> to the BEs to make sure they work properly.
>
> --
> Russ Kaufmann
> MVP - Windows Server - Clustering
> ClusterHelp.com, a Microsoft Certified Gold Partner
> Web http://www.clusterhelp.com
> Blog http://msmvps.com/clusterhelp
>
>
date: Thu, 4 May 2006 19:50:46 -0700
author: Evan Dodds [MSFT]
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