Saturday, February 9, 2008

Zones, delegations and retorts

A zone DNS is a part of the space of the names, constituted from a delegated dominion and its sottodomini that they are not to they time, that it is under a same administrative management and therefore is managed from one or more serveur.

The management of a zone is delegated from the advanced zone through of the records of type NS. As an example, in the zone org there will be a delegation for the zone wikipedia.org to serveur DNS that manages it. For redundancy reasons, ciascuna zone is replied on more server, and consequently the delegation is constituted from more record NS, that they indicate that everyone of the server indicates to you contains the information for that zone (that is is autoritativo for the zone).

Various the serveur that they are delegated for a zone would have to contain the same information, so that one whichever of these can answer to one query for a record of the zone.

The retort outline typically previews that there is a server master (primary), that it is that one on which come modernized the information, and or a more server Slavic (secondary), that they copy the information from the master when necessary. In order to hold trace delle various "versions" of a zone that can are to us in circulation, and particular in order to allow to a secondary one to decide if it must transfer the zone dal primary, every zone has a number of series, that every time must be increased that come made modifications sul primary. In order to obtain the number of series of a present zone on a server, one is carried out interrogation of type SOA. The secondary one confronts just the number of series with that one of the head physician, and if that one of the primary one is advanced it transfers the zone.

The operation of copy of all the records of a zone from the master to one Slavic is said zones transfer, and can be complete (all the content of the zone comes copied) or increases them (comes only copied the records modified regarding the already present version.

Some implementazioni of DNS allow to modify the zones from whichever autoritativo server, propagando the modifications on the other server.

The root (root) of the tree of names DNS is the zone. (point), that it is managed from with of serveur calls root serveur exactly to you.

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