European Internet Registry:

                   Procedures for DNS Delegation

                     in the IN-ADDR.ARPA Domain



                           David Kessens

                             June 1994

                       Document-ID: ripe-105++
                         Obsoletes: ripe-105




                              ABSTRACT

           This document describes the procedures for the
      delegation of zones in European subdomains of
      IN-ADDR.ARPA.



Introduction


The domain tree below IN-ADDR.ARPA is used to facilitate "reverse"
mapping from IP addresses to domain names [RFC883, RFC1033].  This
document describes the procedures for the delegation of zones in
European subdomains of IN-ADDR.ARPA.


Randomly Assigned Numbers


There are two groups of European network numbers: hierarchically assigned
numbers and randomly assigned ones. The hierarchically assigned numbers
are part of the 193.x.y.0 and 194.x.y.0 network blocks. All other
European network numbers, class A, class B and 192.x.y.0 class Cs are
randomly assigned.


Hierarchically Assigned Numbers

The subdomains of IN-ADDR.ARPA corresponding to the hierarchically
assigned network numbers are administered by the RIPE NCC.  These
numbers are currently:


        193.0.0.0 - 194.255.255.255


The other addresses are administered by the other regional registries
that might have other procedures for requesting a reverse delegation.

For clarity we refer in the procedures and examples as described below to
the 193.x block of addresses, although we could have as well used the
other block(s) that RIPE administers.

With the assignment of class C network numbers following RFC1466,
large chunks of the address space are delegated to regional Internet
Registries. The regional registries delegate blocks of class C net-
work numbers to local Internet Registries. In this way a hierarchy
in the address space is created, which is similar to the hierarchy
in the domain name space. Due to this hierarchy the reverse DNS map-
ping can also be delegated in a similar model as used for the
normal Domain Name System.

For instance, the RIPE NCC has been delegated the complete class  C
address space starting with 193. It is therefore possible to
delegate the 193.IN-ADDR.ARPA domain completely to the RIPE NCC,
instead of each and every reverse mapping in the 193.IN-ADDR.ARPA
domain to be registered with the InterNIC. This implies that all
193.IN-ADDR.ARPA delegations in turn will be done by the RIPE NCC.

Even better, since local registries usually receive blocks of 256 class C
networks from the RIPE NCC, the NCC can delegate the reverse
registrations for such complete blocks to these local registries. This
implies that customers of these service providers no longer have to
register their reverse domain mapping with the InterNIC or the NCC, but
the service providers have authority over that part of the reverse
mapping. This decreases the workload on the InterNIC and the RIPE NCC,
and at the same time improves the service a provider can offer its
customers by improving response times for reverse mapping changes.

In order to provide a reliable service some procedures have been agreed
and must be followed in order to avoid confusion and inconsistencies.
These procedures are covered in the procedure section.

The registration of the reverse zones for individual class C net-
works will  usually  be  done  by the registry administering the
class C block this network has been assigned from.

If the subdomain has not yet been delegated to the registry con-
cerned the RIPE NCC will register the individual networks. However
this service is only provided at a "best-effort" level and no ser-
vice guarantees are given.  The local registries should whenever
possible provide this service locally.


Responsibilities for the DNS administrator of a reverse block delegation:


As with all domain name space, running the reverse server for class C
blocks does not imply that one controls that part of the reverse domain.
It only implies that one administers that part of the reverse domain. If
after repeated complaints the delegated name space is still not
administered properly the RIPE NCC has to revoke the delegation.

Before adding individual nets, the administrator of a reverse domain must
check whether all servers to be added for these nets are indeed set up
properly.

There are some serious implications when a customer that uses
address space out of the service provider class C blocks, moves
to another service provider. The  previous service  provider
cannot force its ex-customer to change network addresses, and
will have to continue to provide  the appropriate delegation
records  for reverse mapping of these addresses, even though
they are no longer belonging to a customer.

The registration of the reverse zones for individual  class C
networks  will  usually be done by the registry administering
the class C block this network has been assigned from.  The
registry will make the necessary changes to the zone files.
The registry will also make sure that the network objects in
the RIPE database for these networks are updated with the
correct "rev-srv" attributes.

In case the RIPE NCC receives a request for the reverse zone of
an individual class C network out of a block that has been
delegated, the request will be forwarded to the mailbox speci-
field in the SOA RR for the zone concerned and to the zone-
contact registered in the RIPE database for that zone.

The NCC also suggests that similar procedures are set up for  the
delegation  of reverse zones for individual class C networks from
the registries to individual organisations.









Procedures


The procedure for asking the reverse delegation of a block (256 C's) of
addresses or network (1 or more C's) addresses is quite similar but there
are some differences. Therefor they are described as one procedure with
clear remarks when something only applies for block or network delegations.
Note that we will be a little bit more stringent on the rules for block
delegations since we need to be sure that other people can rely on you
for proper operation of the DNS system.

Above procedures are defined to ensure the necessary high availabil- ity
for the reverse domains, and to minimise confusion.  The NCC will ensure
fast response times for addition requests, and will in principle update
the 193.IN-ADDR.ARPA domain at least once per working day, if needed. Any
problems regarding the reverse zones in 193.IN-ADDR.ARPA should be
reported to <[email protected]>.



 1.  We only reverse delegate when all addresses are assigned to you.

 2.  Your nameservers should be configured and running and should have
     good reachability on the internet. Nameservers for block delegations
     must meet similar connectivity requirements as top-level domain
     servers.

     The NCC recommends to use the following timers and counters (as
     advised by RFC1537):

	 28800	;refresh period (8 hours)
	 7200	;retry interval (2 hours)
	 604800	;expire time    (1 week)
	 86400	;default ttl    (1 day)

     It is mandatory for network (C) reverse delegations:

     - ns.ripe.net is NOT one of the secondary/primary nameservers

     - at least two nameservers should be used

     - We need a RIPE database 'inetnum' object with 'rev-srv:'
       attributes for the name (not IP address) of each nameserver.


     It is mandatory for block reverse delegations:

     - ns.ripe.net is one the secondary (never primary) nameservers

     - at least two other nameservers that don't reside on the same
       ethernet are required

     - Operators of the primary nameservers should be familiar with
       RFC1537 and this document

     - We need a RIPE database 'domain' object for each delegation
       with 'nserver:' attributes for the name (not IP address) of each
       nameserver


 3.  Send an E-mail request to <[email protected]> with:

     - In the header (or body if not possible) of your E-mail message:

       X-NCC-RegID: Country.RegistryName

       This is not required, though easy for keeping track of the
       requests. Of course, we don't need your local registry ID if you
       are not from a RIPE local registry.

     For network (C) reverse delegations:

     - We need a RIPE database 'inetnum' object with 'rev-srv:'
       attributes for the name (not IP address) of each nameserver

     For block reverse delegations:

     - State in your request that you know about RFC1537 & this document

     - A RIPE database 'domain' object for each delegation
       with 'nserver:' attributes for the name (not IP address) of each
       nameserver

 4.  Your request will first go through to an automatic checking program.
     The program will check your zone files and report you about errors
     (that should be fixed), warnings (that you might want to change), or
     that no errors have been found. If errors are found, you will be
     asked to fix them and resubmit your request and the automatic checks
     will be done again.

     If no errors (warnings are allowed, but we strongly suggest that you
     at least take a look at them) are found your request will be
     acknowledged and your request will be forwarded to the person in
     charge of the reverse delegation requests. He/she processes the
     request further. If no additional problems are found the object will
     included in the database and the block/network reverse delegated.
     You will always receive an acknowledgment when the delegation has
     been done or an explanation why not.


Example of a network delegation request:


From: "Anne X. Ample" <[email protected]>
To: RIPE Hostmaster <[email protected]>
Subject: LONGACK 2.1.193.in-addr.arpa delegation please

Please delegate 2.1.193.in-addr.arpa as specified below.

Thank you!

For the AMPLE Corporation

Anne X. Ample


inetnum:   193.1.2.0 - 193.1.3.255
netname:   AMPLE
descr:     AMPLE Corporation
descr:     Amsterdam, Netherlands
country:   NL
admin-c:   Anne X. Ample
tech-c:    G. E. K. Ample
aut-sys:   4711
rev-srv:   ns.ample.nl
rev-srv:   ns.elpma.ln
changed:   [email protected] 930101
source:    RIPE



Example of a block (256 C's) reverse delegation:


From: Marten Terpstra <[email protected]>
To: RIPE Hostmaster <[email protected]>
Subject: LONGACK 202.193.in-addr.arpa delegation please


Dear NCC people,

I have read and understood ripe-105++ and RFC1537.
Could you please delegate 202.193.in-addr.arpa as specified below.

Thank you!

Marten Terpstra


domain:  202.193.in-addr.arpa
descr:   Pan European Organisations class C block
admin-c: Daniel Karrenberg
tech-c:  Marten Terpstra
zone-c:  Marten Terpstra
nserver: ns.eu.net
nserver: sunic.sunet.se
nserver: ns.ripe.net
changed: [email protected] 930319
source:  RIPE



Some notes on the automatic checking program:

You can use some keywords in the 'Subject:' line of your E-mail to
control the checking process. The use of the LONGACK keyword is very
recommended. For changing an existing delegation put the keyword CHANGE
in the 'Subject:' line of your E-mail message.

HELP    - will send you this document
CHANGE  - is needed if you want to change an existing reverse delegation
LONGACK - will give you the most verbose output as possible
TEST    - will only test your zone files without actually doing
          the request


When you want to to a request for a block delegation and you want to know
if there are already reverse zones registered within the zone of the
requested block delegation, just send in your request and you will
receive an error report that includes a copy of our zone file regarding
this zone!