[...]
other servers are more conservative, and had switched to manual daily FTP
of the COM zone longer ago than F has done. (with manual daily FTP you
get the advantages of gzip, and of the pretense of "zone master" status
while you manually retry after timeouts. AXFR needs those properties.)
wouldn't a new transfer type (AZFR/IZFR) be useful here, being basically
AXFR/IXFR but piped through gzip on each end?
These would need to be negotiated (based onversion number) of course,
but would help a lot with large zones like COM...