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     nsupdate [-k keydir:keyname] [-d] [-v] [filename]


     Nsupdate is a program to update Internet domain name servers supporting
     dynamic update.  Nsupdate uses the DNS resolver library to pass messages
     to a DNS server requesting the additional or deletion of DNS resource
     records (RRs).  Nsupdate reads input from filename or standard input.


     -k          Sign updates with TSIG.

     -d          Debug mode.

     -v          Virtual circuit - use TCP to communication with server.  De­
                 fault is UDP.


     Nsupdate reads input records, one per line, each line contributing a re­
     source record to an update request.  All domain names used in a single
     update request must belong to the same DNS zone.  Updates are sent to the
     master server as defined in the SOA MNAME field.  A blank line causes the
     accumulated records to be formated into a single update request and
     transmitted to the zone's authoritative name servers.  Additional records
     may follow, which are formed into additional, completely independent up­
     date requests.  For the last request to be transmitted, a blank line must
     end the input.

     Records take one of two general forms.  Prerequisite records specify con­
     ditions that must be satisfied before the request will be processed.
     Update records specify changes to be made to the DNS database.  A update
     request consists of zero or more prerequisites and one or more updates.
     Each update request is processed atomically - all prerequisites must be
     satisfied, then all updates will be performed.

     Nsupdate understands the following input record formats:

     prereq nxdomain domain-name Requires that no RR of any type exists with
             name domain-name.

     prereq yxdomain domain-name Requires that at least one RR named domain-
             name must exist.

     prereq nxrrset domain-name [class] type Requires that no RR exists of the
             specified type and domain-name.

     prereq yxrrset domain-name [class] type [data...] Requires that a RR ex­
             ists of the specified type and domain-name. If data is specified,
             it must match exactly.

     The following example illustrates the interactive use of nsupdate to
     change an IP address by deleting any existing A records for a domain name
     and then inserting a new one.  Since no prerequisites are specified, the
     new record will be added even if there were no existing records to
     delete.  Note the trailing blank line, required to process the request.

           $ nsupdate
           > update delete test.example.com A
           > update add test.example.com 3600 A

     In this example, a CNAME alias is added to the database only if there are
     no existing A or CNAME records for the domain name.

           $ nsupdate
           > prereq nxrrset www.example.com A
           > prereq nxrrset www.example.com CNAME
           > update add www.example.com 3600 CNAME test.example.com

     In this example, the nsupdate will be signed with the key "mykey", which
     is in the directory "/var/named/keys".

           $ nsupdate -k /var/named/keys:mykey
           > update add ftp.example.com 60 A


     "send error" Typically indicates that the authoritative nameservers could
             not be reached

     "failed update packet" Typically indicates that the nameserver has re­
             jected the update, either because the nameserver doesn't support
             dynamic update, or due to an authentication failure

     "res_mkupdate: packet size = size" (and no other messages) The update was
             successfully received and authenticated by the nameserver.  The
             prerequisites, however, may have prevented the update from actu­
             ally being performed.  The only way to determine if the update
             was performed is to use debug mode (-d) and examine the status
             field in the nameserver's reply.


     initial domain name and name server addresses


     named(8),  resolver(3),  resolver(5);  RFC-1034, ``Domain Names -

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