Editing DNS zone (section)

==Zones for Internet infrastructure==
The top-level domain [[.arpa|arpa]] serves as a delegation zone for various technical infrastructure aspects of DNS and the Internet, and does not implement the registration and delegation system of the country and generic domains.
The name ''arpa'' is a remnant of the [[ARPANET]], one of the predecessor stages of the Internet. Intended as a transitional aid to the DNS, deleting the domain arpa was later found to be impractical. Consequently, the name was officially redefined as an acronym for ''Address and Routing Parameter Area''. It contains sub-zones used for reverse resolution of IP addresses to host names ([[IPv4]]: in-addr.arpa, [[IPv6]]: ip6.arpa), telephone number mapping ([[ENUM]], e164.arpa), and uniform resource identifier resolution (uri.arpa, urn.arpa).

Although the administrative structure of this domain and its sub-domains is different, the technical delegation into zones of responsibility is similar and the DNS tools and servers used are identical to any other zone. Sub-zones are delegated by components of the respective resources. For example,  8.8.2.5.5.2.2.0.0.8.1.e164.arpa., which might represent an E.164 telephone number in the [[ENUM]] system, might be sub-delegated at suitable boundaries of the name. An example of an [[IP address]]es in the reverse DNS zone is 166.188.77.208.in-addr.arpa, which represents the address 208.77.188.166 and resolves to the domain name ''www.example.com''.  In the case of IP addresses, the reverse zones are delegated to the [[Internet service provider]] (ISP) to which the IP address block is assigned. When an ISP allocates a range to a customer, it usually also delegates the management of that space to the customer by insertion of name server resource records pointing to the customer's DNS facilities into their zone, or provides other management tools. Allocations of single IP addresses for networks connected through [[network address translation]] (NAT) typically do not provide such facilities.