Each DNS zone has an SOA record. When you add a zone to a domain, a Start of Authority (SOA) record is automatically created for the zone. This record designates the start of the zone and specifies where in the domain name space the name server has authority. The record also specifies timing information for a zone transfer, which is the process of transferring lookup data from the master name server to the slave server. You can modify the default SOA settings for a zone.