Maximum TSIG wire size is reached only in empty error response with BADTIME.
In most cases reservation of such a size led to early truncation.

...in case when update is re-scheduled by zone_update_enqueue()

This does not big harm on not-frequently updated zones, NOTIFY is simply delayed.
This helps on frequently updated (DDNS or [AI]XFR) zones - NOTIFY is not sent more often than once a second.

Libor Peltan authored 8 years ago and Daniel Salzman committed 8 years ago

instead, if obtaining key by keytag is necessary, we walk through all the matching keys and choose the appropriate one