Debian 10 Doesn’t support DNSSEC:
Implementing would require an update to Bind
NS1 Master for “Websites” hosted on NS1 + Slave for the rest (Create Unique users for each)
NS2 Master for " Websites Hosted on NS2 + Slave for the rest
Server3: Master for Server3 websites
Server4: Master for Server4 websites
NS1 Syncs to NS2
NS2 Syncs to NS1
Server3 Syncs to NS1 and NS2
Server4 Syncs to NS1 and NS2