A DNS zone refers to a certain portion or administrative space within the global Domain Name System (DNS). Each DNS zone represents a boundary of authority subject to management by certain entities. The total of all DNS zones, which are organized in a hierarchical tree-like order of cascading lower-level domains, form the DNS namespace.
The authority over each DNS zone is delegated to a legal entity or organization (i.e. a country-code top-level domain registry) or a company/individual registered to use a certain sub-domain within the system. Depending on the administrative rights delegated to a certain entity, DNS zones may consist of only one domain, or of many domains and sub-domains. Further authority over a sub-space could be delegated to other parties, if necessary.
The DNS Zone file
The DNS Zone file is the representation of the DNS Zone - it is the actual file, which contains all the records for a specific domain. In a DNS Zone file, each line can hold only one record, and each DNS Zone file must start with the TTL (Time to Live), which specifies for how long the records should be kept in the DNS Server's cache. The other mandatory record for a DNS Zone file is the SOA (Start of Authority) record - it specifies the primary authoritative name server for the DNS Zone.
After these two records are specified, additional records, such as A or NS records, can be added. When adding a record for a hostname, the hostname must end with a period (.). Hostnames, which do not end with a period, are considered relative to the main domain name, for which the DNS Zone was created. For example, when specifying the "www" record, there is no need to place a period after it.
Comments in the DNS Zone file must be started with a semicolon (;) and the start of a multiple line comment is represented by brackets ("("), and comments must again start with a semicolon. When the multiple lines end, they must be closed again with a bracket (")"), placed on a single line.
An example of DNS Zone file:
$ORIGIN example.com. ; designates the start of this zone file in the name space $TTL 1h ; The default expiration time of a resource record without its own TTL value example.com. IN SOA ns.example.com. root.example.com. ( 2008120710 ; serial number of this zone file 1d ; slave refresh (1 day) 1d ; slave retry time in case of a problem (1 day) 4w ; slave expiration time (4 weeks) 1h ; minimum caching time in case of failed lookups (1 hour)
) example.com. NS dns1.ntchosting.com. ; ns.example.com is the nameserver for example.com example.com. NS dns2.ntchosting.com. ; ns.somewhere.com is a backup nameserver for example.com example.com. MX 10 mx1.ntchosting.com example.com. MX 10 mx2.ntchosting.com ; mail.example.com is the mailserver for example.com example.com. A 126.96.36.199 ; ip address for "example.com" www A 188.8.131.52
DNS Zone management
It includes a wide range of tasks, such as defining the name hierarchy within the zone, and name registration procedures maintaining the proper operation of the DNS servers. The amount of management actions depends on the size of authority standing behind a particular DNS zone. Through the user-friendly web hostingControl Panel that we, at NTC Hosting, provide you with, you can manage all the records in a DNS zone. DNS management is a feature, offered with all of our web hosting plans.