rndc

rndc talks to named over a control channel (here 127.0.0.1, with a shared key), so a server can take a changed zone without a restart. rndc reload ZONE reads that zone's file again; rndc status shows what it serves. Its counterpart for unbound is unbound-control.

rndc command usage

rndc reload [ZONE]
rndc retransfer ZONE
rndc reconfig
rndc status
rndc flush

Options

reload example.lab

read that zone's file again (all zones without a name)

retransfer corp.lab

on a secondary: copy the whole zone from the primary again

reconfig

read named.conf again, for new options and zones

status

version, zones served, and whether it is running

flush

empty the server's cache (for a resolving BIND)

rndc examples

rndc reload example.lab

Makes BIND serve the zone file as it is now.

rndc status

Shows that named runs and how many zones it serves.

Pitfalls

• Secondaries copy a zone only when its serial is higher: raise it with every edit. A primary set to work out IXFRs from the file (ixfr-from-differences) refuses to load the edit at all, and says so only in its log.
• rndc reload answers zone reload queued before loading: errors in the zone show in the server's log, not on screen.

Run it on real machines