• Good question, thank you. I got it wrong because sadly I did not read the question carefully enough, and performed was the key. Running it does not produce any error, i.e.

    use tempdb;

    go

    dbcc checkalloc with no_infomsgs;

    go

    reports "Command(s) completed successfully."

    The question asked performed not ran, and BOL's verdict is clear:

    In SQL Server 2005 and later, running DBCC CHECKALLOC against tempdb does not perform any checks.

    Oleg