secondary enables serving a zone retrieved from a primary server.
Syntax
secondary [ZONES...]
ZONES zones it should be authoritative for. If empty, the zones from the configuration block
are used. Note that without a remote address to get the zone from, the above is not that useful.
A working syntax would be:
secondary [zones...] {
transfer from ADDRESS
transfer to ADDRESS
upstream ADDRESS...
}
transfer from specifies from which address to fetch the zone. It can be specified multiple times;
if one does not work, another will be tried.
transfer to can be enabled to allow this secondary zone to be transferred again.
upstream defines upstream resolvers to be used resolve external names found (think CNAMEs)
pointing to external names. This is only really useful when CoreDNS is configured as a proxy, for
normal authoritative serving you don't need or want to use this.
Examples
secondary example.org {
transfer from 10.0.1.1
transfer from 10.1.2.1
}