DDNS updates to two master DNS servers

[Scott McCamish (Contractor)]

Hi-  I have two peer DHCP servers successfully updating a master DNS 
server with dynamic updates.  How can I configure the DHCP servers to 
update a second master DNS server? 

Where can I find documentation on this stanza, as found in the 
dhcpd.conf man page:

zone 17.127.10.in-addr.arpa. {
    primary 127.0.0.1;
    key DHCP_UPDATER;
}

Trying to add a second "primary" line throws an error upon startup, 
adding a "secondary" line doesn't seem to complain, but doesn't seem to 
do anything, either.

Thanks for the help.