SQL Server – Default Instance Connecting to Named Instance

sql server

I have 2 instances of SQL Server installed on one server: SQL002.

One instance is a default instance, SQL2008 R2, and the SQL service is generally not running except for specific tests.

The other instance is a named instance, SQL 2014 (so SQL002/SQL2014). This is generally running all the time.

Today I just had a developer tell me that when they connect to SQL002 in SQL Server Management Studio it will connect successfully. I replicated this from my machine and also see a successful connection, however when I look at the properties of the connection it is reporting that it connected to the named instance.

What is going on here? Is there a redirect I'm not aware of?

Best Answer

There can be three reasons:

  • SQL Aliases: either you or that dev has an alias
  • Named instance running on port 1433. Connecting to the default instance means just connecting with port 1433 instead of asking the sql browser first (only applies to tcp)
  • Explicit port inside the connection string
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