fns_dns - overview of FNS over DNS implementation


     Federated  Naming  Service  (FNS)  provides  a  method   for
     federating  multiple  naming services under a single, simple
     interface for the basic naming operations. One of the naming
     services  supported  by FNS is the Internet Domain Name Sys-
     tem, or DNS (see in.named(1M)). DNS is a  hierarchical  col-
     lection  of name servers that provide the Internet community
     with host and domain name  resolution. FNS uses DNS to  name
     entities  globally.  Names can be constructed for any enter-
     prise that is  accessible  on  the  Internet;  consequently,
     names can also be constructed for objects  exported by these

     FNS provides the XFN interface for performing naming resolu-
     tion  on  DNS  domains  and  hosts.  In addition, enterprise
     namespaces such as those served  by  NIS+  and  NIS  can  be
     federated  with  DNS  by  adding  TXT  records  to  DNS.  To
     federate an NIS+ or  NIS  namespace  under  DNS,  you  first
     obtain  the  root  reference  for  the NIS+ hierarchy or NIS
     domain. This reference is referred to  as  the  next  naming
     system  reference because it refers to the  next naming sys-
     tem beneath the DNS domain. This reference contains informa-
     tion  about  how to communicate with the NIS+ or NIS servers
     and has the following format:

          <domainname> <server name> [ <server address> ]

     where <domainname>  is  the  fully  qualified  domain  name.
     Notice  that  NIS+  and NIS have slightly different syntaxes
     for domain names. For NIS+, the fully qualified domain  name
     is case-insensitive and terminated by a dot character ('.').
     For NIS, the fully qualified domain name  is  case-sensitive
     and  is not terminated by a dot character. For both NIS+ and
     NIS, <server address> is optional.  If it is not supplied, a
     host  name  lookup  will  be  performed to get the machine's

     For example, if the machine wiz-nisplus-server with  address  serves the NIS+ domain wiz.com., the reference
     would look like this:

          wiz.com. wiz-nisplus-server

     For NIS, the reference information is of the form:

          <domainname> <server name>

     For example, if the machine woz-nis-server  serves  the  NIS
     domain Woz.COM, the reference would look like this:

          Woz.COM woz-nis-server

     After obtaining this information,  you  then  edit  the  DNS
     table  (see   in.named(1M))  and  add a TXT record with this
     reference information.   The TXT record must  be  associated
     with  a DNS domain that includes an NIS record. For example,
     the reference information shown in the examples above  would
     be entered as follows.

     For NIS+:

          TXT     "XFNNISPLUS     wiz.com.     wiz-nisplus-server

     For NIS:

          TXT "XFNNIS woz.com woz-nis-server"

     Note the mandatory double quotes ('"') delimiting  the  con-
     tents  of  the  TXT record.  After making any changes to the
     DNS table, you must notify the server by  either  restarting
     it or sending it a signal to reread the table:

          #kill -HUP `cat /etc/named.pid`

     This update effectively adds the next naming  system  refer-
     ence   to   DNS.  You  can  look  up  this  reference  using
     fnlookup(1) to see if the information has been  added  prop-
     erly.  For  example, the following command looks up the next
     naming system reference of the DNS domain Wiz.COM:

          #fnlookup -v .../Wiz.COM/

     Note the mandatory trailing slash ('/').

     After this administrative step has been taken, clients  out-
     side of the NIS+ hierarchy or NIS domain can access and per-
     form operations on the contexts in the NIS+ hierarchy or NIS
     domain.  Foreign  NIS+ clients access the hierarchy as unau-
     thenticated NIS+ clients. Continuing the example above,  and
     assuming  that  NIS+  is federated underneath the DNS domain
     Wiz.COM, you can now list the root of  the  NIS+  enterprise
     using the command:
           #fnlist .../Wiz.COM/


     fnlist(1), fnlookup(1), nis+(1),  in.named(1M),  ypserv(1M),
     xfn(3XFN),       fns(5),       fns_nis(5),      fns_nis+(5),
     fns_references(5), fns_x500(5)

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