Both above are true.
unbound is used as the DNS server on IPFire.
bind is also installed but only used to provide the utilities
- dig
- host
- nslookup
- nsupdate
and the libraries
- libbind9
- libdns
- libirs
- libisc
- libisccc
- libisccfg
- libns
for those applications used in IPFire that require certain bind libraries to be linked in for their usage.
bind is not used as a dns server on IPFire.