SQL Server Authentication vs Windows Authentication Good Afternoon,

I've been working on a problem where connecting to a remote default SQL instance (using the server's IP address) via Windows Authentication has been taking a lot longer than SQL Authentication.

Originally I thought that the problem was down to reverse DNS lookups but now I am not too sure. There was a record in the forward lookup zone for the server so connections using the server's name were quick. Once a record for the server was entered into the reverse lookup zone, the connections using the server's IP address were much faster.

So the issue appears to be fixed but I'm not so sure. Why wouldn't SQL authenticated connections have a similar problem? Do SQL authenticated connections not resolve against DNS?

Does anyone have any links to documentation on the internals of the two types of connections? I've been doing some research but have come up short.

Any links or advice would most appreciated.

Andrew
For Windows Authentication "SQL Server validates the account name and password using the Windows principal token in the operating system."

For SQL Server Authentication "logins are created in SQL Server that are not based on Windows user accounts. Both the user name and the password are created by using SQL Server and stored in SQL Server."

So SQL Server authenticated connections do not use DNS.

See this topic "Choose an Authentication Mode" in MSDN: http://msdn.microsoft.com/en-us/library/ms144284.aspx

EDIT: Even with SQL Server Authentication the initial connection to the SQL Server requires resolution of the SQL Server's name. It is, however, also possible to connect to the SQL Server using only the IP Address as you noted above.  

See SQL Server name formats at:
http://msdn.microsoft.com/en-us/library/ms188642.aspx