multi-master configuration?

[Jiann-Ming Su]

How does multi-master configuration work?  The scenario I have is three ISC DHCP 
servers configured for dynamic DNS, which also act as primary for the dynamic 
zone (dyn.mydomain.com):

zone "dyn.mydomain.com" {              
        type master;
        file "ddb.dyn.mydomain.com";
        allow-update { key DHCP_UPDATER; };
};

These three dhcp/dns servers do not respond to DNS queries.  My infrastructure 
DNS consists of a DNS master (192.168.25.1) that is a slave for 
dyn.mydomain.com:

zone "dyn.mydomain.com" {
        type slave;
        file "ddb.dyn.mydomain.com";
        masters { 172.30.8.0; };
};

Obviously, I only have a single master listed above.  I know I'll have to list 
the other two, and set "multi-master yes".  

The secondary servers that actually handle user dns requests slave to the master 
(192.168.25.1):

zone "dyn.mydomain.com" {
        type slave;
        file "ddb.dyn.mydomain.com";
        masters { 192.168.25.1; };
};

So, to clarify my question.  When I add the other two dhcp servers to the 
masters{} list and set "multi-master yes" will this allow all three dhcp servers 
to update the dyn.mydomain.com zone?  If so, do the three dhcp servers also 
update each other? 

Thanks for any insight.