Use a DNS alias for SSAS 2005/2008 instance

You would like to configure a DNS alias (CName) for each server to  redirect transparently clients for high availability.

There is no indication against to use a DNS alias, you can use CNAME to connect to SSAS 2005 or greater. However there are some considerations to take into account.

1. Be carefully on cluster system

2. Be sure that you can “reverse lookup” the CNAME / Alias. SSAS has to reverse lookup the hostname during connection 

3.  Changing the DNS Alias: DNS caching might cause some delay
- Client side cache: It can be cleared with ipconfig /flushdns
- Server Side cache : Depends on the structure, by multilevel structure multiple caches might exist Clearcache possible with dnscmd or GUI (there are settings for the cache lifetime but it is not recommended to change them (it might increase the traffic on the DNS server))

4. Cannot connect locally to your SSAS instance using DNS alias

5.  As the alias uses only server name you cannot configure the protocol , the name of the instance or the port.

6.  At kerberos level you can have false SPN. The SPN needs to be re-registered on the alias name too.

7.  At TCP level you can have errors

8.  DNS will no provide an port information to clients.  If Default instance is listening on a non-default port (SQL Browser cannot redirect) , then port has to be defined in the connection string.

You can create a DNS alias following this article kb: How to set up application names in SQL Server 2000 Analysis Services

Connect bug: Create and alias to a (named) instance of Analysis Services 2005/2008


Michel Degremont | Premier Field Engineer - SQL Server Core Engineer |