self hosting DNS - PTR ignoring out-of-zone data

XX.171.43.179.in-addr.arpa.      1800      IN      PTR      my.domain.

And named throwing

ignoring out-of-zone data (XX.171.43.179.in-addr.arpa)

The syntax looks alright, or does it? searching the web has not produced some remedy.

Well, it seems that a slightly (just a .) different syntax does satisfy named (bind 9.9.4)

XX.171.43.179.in-addr.arpa      1800      IN      PTR      my.domain.