What Is Zone (DNS) Domain Name System And Reverse DNS
What Is Zone (DNS) Domain Name System And Reverse DNS?
Zone (DNS) Domain Name System
In the Domain Name System (DNS) of the Internet zone means that portion of the domain tree for which a name server in charge (also referred to NS) and is therefore familiar with the official data. A zone is managed by a primary name server. To increase the availability of server failures, it is customary to reflect a zone to one or more secondary name servers.
A zone consists of resource records that are stored in a zone file. The original file is located on the primary name server (also called “master” referred to). From there it will be for changes by zone transfer to the secondary name servers also “slave (called the transfer). The terms zone and zone file are interchangeable in almost all situations.
A zone can include an entire domain. Typically, sub-domains but are represented by their own zones. With pointers – the NS resource records (RR-NS) – reference is made to sub-zones, which can be located on other name servers. This process is called delegation: A zone delegation of authority for a sub-domain, and knows only the person or persons responsible name server. Sub-domain requests to be forwarded to the appropriate nameservers. The transition between two zones is, in part zone cut, because cut out by a delegation of a zone from a domain “is.
The top level domain, for example, contains en including all subdomains several million DNA records. It is impossible to keep them in a single zone file. Which belongs to the domain de zone file therefore contains mostly references to the direct subdomains. Pro be separate name servers for a sub-domain exists while a NS record.
From the domain associated zone file can deduce that there are two sub-domains and that the authoritative name server for the nameserver einkauf.example.com-1 and produktion.example.com. The nameserver is 2. The domains and einkauf.example.com produktion.example.com can of course turn contain further sub-domains that can be represented by its own zone files.
Difference between domain and zone
A domain includes the whole child DNS namespace. A domain can be divided into several zones by delegation of authority for subdomains. We also speak of a zone, if we think the physical realization – that is, what server and what are the DNS zone file entries.
The juxtaposition of the domain name (labels) defined on the domain tree and the NS RRs constructed tree zones are nearly identical. In rare cases, a single zone file may contain multiple domains. The area tree is therefore slightly smaller than the domain tree.
Reverse DNS
Reverse DNS lookup (rDNS) refers to a DNS request is to be determined in an IP address of the name. Alternative names are inverse Anfragen1), or inverse reverse lookup requests. The counterpart to the phone is the so-called inverse, so the search for the name to a given phone number.
Reverse DNS Background
In most cases, the Domain Name System (DNS) is used to determine a domain name to its IP address. But there is also the reverse situation, is required for a given IP address of the name. If this resolution is to be allowed to be created a reverse domain.
Technology [edit]
Since it would be extremely time consuming to search for an inverse question the entire domain tree to the desired IP address – it is not well known, in which branch of the desired item is located – has established a separate domain for inverse requests, in -addr.arpa domain. Below this domain, only there are three sub-domain levels, so that a maximum of three steps are necessary to resolve an IP address.
The immediate subdomains of in-addr.arpa as a label have a number between 0 and 255 and represent the first component of an IP address. The next level in the tree represents the second component of an IP address and the lowest level, is the third component. As is evident, this includes a reverse name of the IP address components in reverse order. This structure enables a refining of the reverse address space in several steps. All newly assigned IP addresses from this segment will be entered there. At a later stage subdomains can be created. Inverse queries to IP addresses for which there are no sub-domains are resolved while continuing on the global domain.
Reverse domains work just like normal. This applies mainly to the associated zone files. At the beginning of a reverse domain zone file associated with an SOA resource record is followed by one or more NS resource records. As an additional RR types but are only allowed PTR resource records. For a PTR RR is on the left and right of an IP address a name – in contrast to the A resource record, left a name and an IP right, where is address.
Study: From Wikipedia, the free encyclopedia. The text is available under the Creative Commons.
