A DNS zone is any distinct, contiguous portion of the domain name space in the (DNS) Domain Name System for which administrative responsibility has been delegated to a single manager.
The domain name space of the Internet is organized into a hierarchical layout of subdomains below the DNS root domain.
The individual domains of this tree may serve as delegation points for administrative authority and management.
However, usually it is furthermore desirable to implement fine-grained boundaries of delegation, so that multiple sub-levels of a domain may be managed independently.
Therefore the domain name space is partitioned into areas (zones) for this purpose.
A zone starts at a domain and extends downward in the tree to the leaf nodes or to the top-level of subdomains where other zones start.
A DNS zone is implemented in the configuration system of a domain name server.
Historically, it is defined in the zone file, an operating system text file that starts with the special DNS record type (SOA) Start of Authority
and contains all records for the resources described within the zone.
This format was originally used by the (BIND) Berkeley Internet Name Domain Server software package, and is defined in RFC 1034 and RFC 1035.
An SOA record is a Start of Authority. Every domain must have a Start of Authority record at the cutover point where the domain is delegated from its parent domain. For example, if the domain distributednetworks.com is delegated to DNSimple name servers, we must include the SOA record for the name distributednetworks.com in our authoritative DNS records.
We add this record automatically for every domain added to DNSimple. We show this record to you as a System Record on your domain's Manage page.