The domain name must be registered with the administrator to avoid
      name conflicts and to make the domain related information
      available to other domains.  The central administrator may have
      further requirements, and a domain is not registered until the
      central administrator agrees that all requirements are met.

      There must be a responsible person associated with each domain to



 

RFC 882                                                    November 1983
                                  Domain Names - Concepts and Facilities


      be a contact point for questions about the domain, to verify and
      update the domain related information, and to resolve any problems
      (e.g., protocol violations) with hosts in the domain.

      The domain must provide redundant (i.e., two or more) name servers
      to provide the name to address resolution service.  These name
      servers must be accessible from outside the domain (as well as
      inside) and must resolve names for at least all the hosts in the
      domain.

      Once the central administrator is satisfied, he will communicate
      the existence to the appropriate administrators of other domains
      so that they can incorporate NS records for the new name server
      into their databases.

   Name server logic

      The processing steps that a name server performs in responding to
      a query are conceptually simple, although implementations may have
      internal databases that are quite complex.

      For purposes of explanation, we assume that the query consists of
      a type QTYPE, a class QCLASS, and a domain name QNAME; we assume
      that the name server stores its RRs in sets where each set has all
      of the RRs for a particular domain.  Note that this database
      structure and the following algorithms are meant to illustrate one
      possible implementation, rather than a specification of how all
      servers must be implemented.

      The following notation is used:

      ord(DOMAIN-NAME)     returns the number of labels in DOMAIN-NAME.

      findset(DOMAIN-NAME) returns a pointer to the set of stored RRs
                           for DOMAIN-NAME, or NULL if there is no such
                           information.

      set(POINTER)         refers to a set located previously by
                           findset, where POINTER is the value returned
                           by findset.

      relevant(QTYPE,TYPE) returns true if a RR of the specified TYPE is
                           relevant to the specified QTYPE.  For
                           example, relevant(MAILA,MF) is true and
                           relevant(MAILA,NS) is false.

      right(NAME,NUMBER)   returns a domain name that is the rightmost
                           NUMBER labels in the string NAME.




 

RFC 882                                                    November 1983
                                  Domain Names - Concepts and Facilities


      copy(RR)             copies the resource record specified by RR
                           into the response.

      The name server code could be represented as the following
      sequence of steps:

     {    find out whether the database makes this server          
          authoritative for the domain name specified by QNAME   } 

     for i:=0 to ord(QNAME) { sequence through all nodes in QNAME }
     do   begin                                                    
          ptr:=findset(right(QNAME,i));                            
          if ptr<>NULL                                             
          then { there is domain data for this domain name }       
               begin                                               
               for all RRs in set(ptr)                             
               do   if type(RR)=NS and class(RR)=QCLASS            
                    then begin                                     
                         auth=false;                               
                         NSptr:=ptr                                
                         end;                                      
               for all RRs in set(ptr)                             
               do   if type(RR)=SOA and class(RR)=QCLASS           
                    then auth:=true                                
                    end