Moin,
I dug a bit into this topic, but unfortunately my article is in German only: Q&A: Worauf wird beim Passwortqualitätscheck getestet?
The palindrome check is part of a fixed set of tests that are carried out by a component called “cracklib”. It’s enforcement can be configured by activating a password policy with the “Password quality check” enabled (see also: How-to: Align Password Policies across Directory Services).
Regards
Jan-Luca