Exchange 2007 and 2010 Autodiscovery DNS SRV record for BIND
Published: 09-05-2013 | Author: Remy van Elst | Text only version of this article
Table of Contents
Note: This article is targeted at *NIX administrators who have to manageExchange installations, but are not Microsoft specialists. Therefore the BINDsetup does not have an explanation, but the Exchange part has.
What is Exchange Autodiscovery
Exchange 2007/2010 Autodiscovery is the ability for Outlook to automaticallyconfigure itself to an Exchange 2007/2010 server. The main benefit is for remoteusers to use Outlook on the Internet as if it was connected on the LAN, this iscalled Outlook Anywhere or Outlook RPC over HTTP. This is very easilyaccomplished by having a specific DNS record available for the domain.
How does Exchange Autodiscovery work?
Outlook has a few ways to look for domain information when configuring itselfbased on the users email address. Lets say I want to set up Outlook as
email@example.com, but my site does not have the required Autodiscovery XMLfiles set up. I enter that email address in Outlook, now Outlook do thefollowing things to get its information:
- Autodiscover posts to https://example.org/Autodiscover/Autodiscover.xml. This fails.
- Autodiscover posts to https://autodiscover.example.org/Autodiscover/Autodiscover.xml. This fails.
- Autodiscover performs the following redirect check: GET http://autodiscover.example.org/Autodiscover/Autodiscover.xml. This fails.
- Autodiscover uses DNS SRV lookup for autodiscover. tcp.example.org, and then "mail.example.org" is returned.
- Outlook asks permission from the user to continue with Autodiscover to post to https://mail.example.org/autodiscover/autodiscover.xml.
- Autodiscover's POST request is successfully posted to https://mail.example.org/autodiscover/autodiscover.xml.
There are various reasons not to set up the Autodiscovery XML on the mainwebsite or the Autodiscover.example.org. Mainly because it requires extracertificates, IP addresses and maintenance. Maybe a company does not haveWindows servers to host their main website, or they don't want the hassle. Inthose cases the DNS SRV record works very nice.
BIND DNS Record
The following record line should be put in your zone config file(
; Exchange autodiscovery_autodiscover._tcp IN SRV 0 0 443 mail.example.org.
rndc reload you should be able to use the Autodiscovery servicewithout problems. It is tested with BIND 9.8.