Does DNS Cluster require ssh access to remote servers?

Hello, We are running three DNS-Only servers that are used as nameservers (ns1/ns2/ns3.domain.com). Our web servers are all connected using DNS Cluster, to each nameserver. For maximum security, we want to use the Host Access Control to disallow all ssh access to the server except our own IPs. (We want to create a rule like this: [QUOTE]ssh 1.2.3.4 allow # Our IP address sshd ALL deny
Will this setup cause any problems with the webservers and nameservers trying to connect to each other to make DNS updates? In other words.. how exactly are DNS updates "sent" from the web servers to the DNS-Only nameservers? Is it using ssh? Or http? or https? Or something else? Thanks.