193.in-addr.arpa procedures v1.4

Here's version 1.4 of the 193.in-addr.arpa delegation procedures. I have
included Piet's recommended timer values, and the comment on reachability of
servers for zones for individual nets.

Please note that the second part of these procdures (single net delegations
done by the NCC) is NOT yet in operation. Single net delegations in 193.x.y
still have to be requested from hostmaster at ripe.net. After next weeks RIPE
meeting we hope to implement the automatic procedure as soon as possible. The
code is there, the operational environment isn't yet ;-)

-Marten



			Guidelines for the delegation
		   of zones in the 193.in-addr.arpa domain

			       Marten Terpstra

				 April 1993

				    V1.4


Introduction

This document describes the procedures for the delegation of authority
of zones in the 193.in-addr.arpa domain.  As of March 16th 1993 the RIPE
NCC has been delegated the authority for the 193.in-addr.arpa domain
from the root.  Due to the fact that in the 193.x.y address space blocks
of 256 class C network numbers are further delegated to local registries
, the possibility exists to also delegate the zone for these blocks in
the 193.in-addr.arpa domain.  This document describes some guidelines
and procedures for this type of delegation and the delegation of reverse
zones for individual class C networks in 193.x.y. 


A bit more explained

With the assignment of class C network numbers following the CIDR (RFC
1338) model, in which large chunks of the address space are delegated to
one region, and within that region blocks of class C network numbers are
delegated to service providers and non-provider registries, some
hierarchy in the address space is created, similar to the hierarchy in
the domain name space.  Due to this hierarchy the reverse Domain Name
System mapping can also be delegated in a similar model as used for the
normal Domain Name System.  For instance, the RIPE NCC has been assigned
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 resistrations will be done by the RIPE NCC.  Even
better, since service providers receive complete class C network blocks
from the RIPE NCC, the RIPE 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 root, but the service provider 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 increase
the service a provider can offer its customers by improve response times
for reverse mapping changes . However there are some things that need to
be examined a bit more closely to avoid confusion and inconsistencies. 
These issues are covered in the next section. 


Procedures for the delegation of direct subdomains of 193.in-addr.arpa

1. A secondary nameserver at ns.ripe.net is mandatory for all blocks of
class C network numbers delegated in the 193.in-addr.arpa domain. 

2. Because of the increasing importance of correct reverse address
mapping, for all delegated blocks a good set of secondaries must be
defined.  There should be at least 2 nameservers for all blocks
delegated, excluding the RIPE NCC secondary. 

3. The delegation of a class C block in the 193.in-addr.arpa domain can
be requested by sending in a domain object for the RIPE database to
<hostmaster at ripe.net> with all necessary contact and nameserver
information.  The RIPE NCC will then forward all current reverse zones
inside this block to the registry, and after addition of these by the
registry, the NCC will check the working of the reverse server.  Once
everything is setup properly, the NCC will delegate the block, and
submit the database object for inclusion in the database.  An example
domain object can be found at the end of this document. 

4. All reverse servers for blocks must be reachable from the whole of
the Internet.  In short, all servers must meet similar connectivity
requirements as top-level domain servers. 

5. 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. 

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

7. There are some serious implications when a customer of a service
provider 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 it they are no longer
belonging to a customer. 

8. 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, and update the network objects in the
RIPE database for these networks, to reflect the correct "rev-srv"
fields.  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 zone contact for this reverse
block. 

9. The NCC advises the following timers and counters for direct subdomains
of 193.in-addr.arpa: 8 hours refresh (28800 seconds), 2 hours retry (7200
seconds), 7 days expire (604800 seconds) and 1 day Time To Live (86400
seconds). The retry counter should be lowered where connectivity is
unstable.

Above procedures are defined to ensure the necessary high availability
for the 193 reverse domains, and to minimize confusion.  The NCC will
ensure fast repsonse times for addition requests, and will in principle
update the 193.in-addr.arpa domain at least once per working day. 

Example domain object to request a block delegation

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: marten at ripe.net 930319
source:  RIPE



Procedures for the delegation of individual network zones by the RIPE NCC.

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.  In case the zone corresponding to
the class C block has not been delegated, the RIPE NCC will
automatically add the reverse nameserver as specified in the "rev-srv"
attribute of the RIPE database object for this network, using the
following procedures:

1. Because of the increasing importance of correct reverse address
mapping, for all delegated networks a good set of secondaries must be
defined.  There should be at least two nameservers for all networks
delegated. 

2. The "rev-srv" field should ONLY contain one fully qualified domain
name of a nameserver which is authoritative for the reverse zone for
this network. 

3. If a network has or is going to have any external connectivity, it is
strongly recommended that it has at least one reverse nameserver that can
be reached from all of the Internet.

4. The checking and addition of the reverse zones for single networks is
completely automated at the RIPE NCC.  Although we do our best to check
the setup of the nameservers, these does not receive the same level of
scrutiny as nameservers for blocks of class C network numbers.  It is
the responsibility of the network contacts to ensure proper operation. 

5. Any problems regarding the reverse zones in 193.in-addr.arpa should
be directed to <hostmaster at ripe.net>. 

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.