DNS Server Technical Specifications

Resolution from domain names to IP addresses for devices or resources connected to the Internet or local area networks (LAN)
Master, slave, and forwarding zones that ensure high availability of DNS service
Flexible migration of DNS service through robust backup and restoring

Supported resource records: A, AAAA, CAA, CNAME, MX, NS, PTR, SPF, SRV, and TXT
Manages DNS zones of the domain created by Synology Directory Server
Listens on IP address changes of network interfaces to update DNS host records automatically (for AD zones only)
Provides access control for zone transferring, DNS queries, and dynamic zone updates
Safeguards the following mechanisms via TSIG (Transfer Signature) keys:
- Synchronization of DNS files
- Dynamic updates from master zones
Sends recursive queries to resolve external DNS records
Supports forwarders for resolving external DNS records
Supports slave zone notifications
Supports importing and exporting zone settings and resource records
Supports split-horizon DNS, providing each client with customized DNS information
Supports forward and reverse DNS lookups
Supports searching and exporting logs
Supports customizing the amount of system resources used by DNS activities:
- Maximum cache size
- Maximum cache TTL (Time-to-live)
- Maximum number of recursive clients
- Maximum number of TCP connections
- Maximum log size

Backup and restoring performed by Hyper Backup are only supported on DSM 5.1 or above
For Synology Directory Server's zones, access control for slave zone notifications is integrated to that of zone transfer limitation
Listening on IP address changes of network interfaces only triggers updates of the default domain name in Synology Directory Server's zones