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This document describes the procedures for the delegation of au-
thority of zones in the domain. As of March
16th 1993 the RIPE NCC has been delegated the authority for the 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 ex-
ists to also delegate the zone for these blocks in the domain.
RIPE community's current IPv4 address allocation and assignment policies. They were developed through a bottom-up, consensus driven, open policy development process in the RIPE Address Policy Working Group (AP WG). The RIPE Network Coordination Centre (RIPE NCC) facilitates and supports this process. These policies apply to the RIPE NCC and the Local Internet Registries (LIRs) within the RIPE NCC service region.

Information on the Address Policy WG is available at: Link: /community/wg/active-wg/ap/

1.0 Introduction

The RIPE NCC is an independent association and serves as one of five Regional Internet Registries (RIRs). Its service region incorporates Europe, the Middle East, and Central Asia. The RIPE NCC is responsible for the allocation and assignment of Internet Protocol (IP) address space, Autonomous System Numbers (ASNs) and the management of reverse domain names within this region. The distribution of IP space follows the hierarchical scheme described in the document "Internet Registry System Link: /membership/internet-governance/internet-technical-community/the-rir-system/ ".

1.1 Scope

This document describes some guidelines and
procedures for this type of delegation and the delegation of re-
verse 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 policies for the responsible management of globally unique IPv4 Internet address space in the RIPE NCC service region. The policies documented here apply to all IPv4 address space allocated and assigned by the RIPE NCC. These policies must be implemented by all RIPE NCC member LIRs.

This document does not describe policies related to AS Numbers, IPv6, Multicast, or private address space. Nor does it describe address distribution policies used by other RIRs. The RIPE community's policies for ASN assignment and IPv6 are published in the RIPE Document Store at: Link:

2.0 IPv4 Address Space

For the purposes of this document, IP addresses are 32-bit binary numbers used as addresses in the IPv4 protocol. There are three main types of IPv4 addresses:

  1. Public IP addresses are distributed to be globally unique according to the goals described in Section 3 of this document. The two types of IPv4 address described in this document are Provider Aggregatable (PA) and Provider Independent (PI).
  2. Some address ranges are set aside for the operation of private IP networks. Anyone may use these addresses in their private networks without registration or co-ordination. Hosts using these addresses cannot directly be reached from the Internet. Such connectivity is enabled by using the technique known as Network Address Translation (NAT). Private addresses restrict a network so that its hosts only have partial Internet connectivity. Where full Internet connectivity is needed, unique, public addresses should be used. 
    For a detailed description of “Address Allocation for Private Internets” and the actual ranges of addresses set aside for that purpose, please refer to RFC 1918 found at: Link:
    For information on the “Architectural Implications of NAT”, please refer to RFC 2993, found at: Link:
  3. Some address ranges are reserved for special use purposes. These are described in the IANA IPv4 Special-Purpose Address Registry Link: and are beyond the scope of this document. 

3.0 Goals of the Internet Registry System

Public IPv4 address assignments should be made with the following goals in mind:

  1. Uniqueness: Each public IPv4 address worldwide must be unique. This is an absolute requirement guaranteeing that every host on the Internet can be uniquely identified.
  2. Aggregation: Distributing IPv4 addresses in an hierarchical manner permits the aggregation of routing information. This helps to ensure proper operation of Internet routing.
  3. Fairness: Public IPv4 address space must be fairly distributed to the End Users operating networks.
  4. Registration: The provision of a public registry documenting address space allocations and assignments must exist. This is necessary to ensure uniqueness and to provide information for Internet troubleshooting at all levels.

3.1 Confidentiality

Internet Registries (IRs) have a duty of confidentiality to their registrants. Information passed to an IR must be securely stored and must not be distributed wider than necessary within the IR. When necessary, the information may be passed to a higher-level IR under the same conditions of confidentiality.

3.2 Language

Please note that all communication with the RIPE NCC must be in English.

4.0 Registration Requirements

All assignments and allocations must be registered in the RIPE Database. This is necessary to ensure uniqueness and to support network operations. 

Only allocations and assignments registered in the RIPE Database are considered valid. Registration of objects in the database is the final step in making an allocation or assignment. Registration data (range, contact information, status etc.) must be correct at all times (i.e. they have to be maintained).

5.0 Policies and Guidelines for Allocations

An allocation is a block of IPv4 addresses from which assignments are taken.

All LIRs receiving address space from the RIPE NCC must adopt a set of policies that are consistent with the policies formulated by the RIPE community and described in this document.

5.1 Allocations made by the RIPE NCC to LIRs

Details of how to join the RIPE NCC can be found in the RIPE Document "Procedure for Becoming a Member of the RIPE NCC Link: /membership/member-support/become-a-member/ "

On application for IPv4 resources LIRs will receive IPv4 addresses according to the following:

  1. All allocation requests are placed on a first-come-first-served waiting list. No guarantees are given about the waiting time.
  2. The size of the allocation made will be exactly one /24.
  3. The sum of all allocations made to a single LIR by the RIPE NCC is limited to a maximum of 256 IPv4 addresses (a single /24). If this allocation limit has been reached or exceeded, an LIR cannot request an IPv4 allocation under this policy.

In case an allocation of a single /24 as per clause 1 can no longer be made, no allocation is to be made until the RIPE NCC recovers enough address space to allocate contiguous /24 allocations again.

5.2 Address Recycling

Any IPv4 address space that was originally assigned by the RIPE NCC for exclusive use by Internet Exchange Points (IXPs) will be added to the reserved IXP pool upon return.

Other address space blocks of a /24 or larger that are returned to the RIPE NCC will be covered by the same rules as the address space intended in section 5.1 – smaller blocks will be put into the reserved pool for IXP use.

This section only applies to address space that is returned to the RIPE NCC and that will not be returned to the IANA but re-issued by the RIPE NCC itself.

5.3 Sub-allocations

Sub-allocations are intended to aid the goal of routing aggregation and can only be made from allocations with a status of "ALLOCATED PA". LIRs holding "ALLOCATED PI" or "ALLOCATED UNSPECIFIED" allocations may be able to convert them to PA allocations if there are no ASSIGNED PI networks within it. The meanings of the various "status:" attribute values are described in Section 7.0.

LIRs wishing to convert their allocations to PA status must contact the RIPE NCC by email at [email protected] Link: mailto:[email protected] .

LIRs may make sub-allocations to multiple downstream network operators.

The LIR is contractually responsible for ensuring the address space allocated to it is used in accordance with the RIPE community's policies. It is recommended that LIRs have contracts requiring downstream network operators to follow the RIPE community's policies when those operators have sub-allocations.

Sub-allocations form part of an LIR's aggregatable address space. As such, an LIR may want to ensure that 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 there-
fore possible to delegate the domain completely
to the RIPE NCC, instead of each and every reverse mapping in the domain to be registered with the INTERNIC. This
implies that all resistrations will be done by
the RIPE NCC. Even better, since service providers receive com-
plete 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 work-
load on the INTERNIC and the RIPE NCC, and at the same time in-
crease 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

1. A secondary nameserver at is mandatory for all
blocks of class C network numbers delegated in the domain.

2. Because of the increasing importance of correct reverse ad-
dress 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
domain can be requested by sending in a domain object for the
RIPE database to <[email protected]> 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 proper-
ly, the NCC will delegate the block, and submit the database ob-
ject 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 im-
plies 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 ser-
vice provider that uses address space out of the service provider
class C blocks, moves to another service provider. The
not retained by a downstream network if the downstream network operator ceases to receive connectivity from the LIR's network. LIRs not wishing to lose address space in this way are responsible for ensuring that the status of the sub-allocation is clear in any contracts between the LIR and the downstream network operator.

5.4 Transfers of Allocations

The transfer of Internet number resources is governed by the RIPE Document, "RIPE Resource Transfer Policies Link: ".

6.0 Policies and Guidelines for Assignments

6.1. Assignments to Internet Exchange Points

A /15 will be held in reserve for exclusive use by Internet Exchange Points (IXPs). On application for IPv4 resources, an IXP will receive a single number resource block according to the following:

  1. Organisations receiving space under this policy must be IXPs and must meet the definition as described in section two of the RIPE Document "IPv6 Address Space for Internet Exchange Points Link: ".
  2. This space will be used to run an IXP peering LAN only; other uses are forbidden.
  3. Assignments will only be made to IXPs that have applied for an IPv6 assignment for their peering LAN (or have already received one).
  4. New IXPs will be initially assigned a /26 by default. Once more than 50% of the initial assignment has been utilised, IXPs can request an assignment up to a /24. In this case, the IXP must return the existing assignment (or existing PI previously issued for their IXP peering LAN).
  5. Once IXPs require an assignment larger than /24, they must return their current one (or existing PI used as an IXP peering LAN) and receive a replacement up to maximum of a /22. After one year, utilisation of the new assignment must be at least 50%, unless special circumstances are defined.
  6. If there are no more assignments of /26 available, smaller assignments can be made.
  7. IXPs holding other PI IPv4 space for their peering LAN (i.e. they are seeking a larger assignment), and any IPv4 space assigned from this pool that is no longer in use, must be returned to the pool within 180 days of disuse or a new assignment. 

6.2 Network Infrastructure and End User Networks

When an LIR holding an IPv4 address allocation makes IPv4 address assignments, it must register these assignments in the RIPE Database.

These registrations can either be made as individual assignments or by inserting an object with a status value of 'AGGREGATED-BY-LIR'.
In case of an audit, the LIR must be able to present statistics showing the number of individual assignments made in all objects with a status of 'AGGREGATED-BY-LIR'.

6.3 Validity of an Assignment

An assignment is valid as long as the original criteria on which it was based remain valid and it is properly registered in the RIPE Database. Changes to the original criteria must be documented in the RIPE Registry, or the assignment will no longer be considered valid. An assignment that was based on information that turns out to be incorrect is no longer valid.

6.4 Transfers of PI space

The transfer of Internet number resources is governed by the RIPE Document, "RIPE Resource Transfer Policies Link: ".

7.0 Types of Address Space

LIRs are allocated Provider Aggregatable (PA) address space. They sub-allocate and assign this to downstream networks. If a downstream network or End User changes its service provider, the address space assigned or sub-allocated by the previous
service provider cannot force its ex-customer to change network
addresses, and
must be returned and the network renumbered.

Clear contractual arrangements are mandatory for PA space. End Users requesting PA space must be given this or a similar warning:

Assignment of this IP space is valid as long as the criteria for the original assignment are met and only for the duration of the service agreement between yourself and us. We have the right to reassign the address space to another user upon termination of this agreement or an agreed period thereafter. This means that you 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
re-configure the addresses of all equipment using this IP space if you continue to require global uniqueness of those addresses.

LIRs will register the type of any assigned address space using the "status:" attribute of the inetnum object in the RIPE Database. The possible values of this attribute are:

  • ALLOCATED PA: This address space has been allocated to an LIR and no assignments or sub-allocations made from it are portable. Assignments and sub-allocations cannot be kept when moving to another provider.
  • ALLOCATED UNSPECIFIED: This address space has been allocated to the RIPE NCC or other RIRs for further distribution. If the address space is administered by the RIPE NCC, more specific objects with other values may exist.
  • SUB-ALLOCATED PA: This address space has been sub-allocated by an LIR to a downstream network operator that will make assignments from it. All assignments made from it are PA. They cannot be kept when moving to a service provided by another provider.
  • LIR-PARTITIONED PA: This allows an LIR to document distribution and delegate management of allocated space within their organisation. Address space with a status of LIR-PARTITIONED is not considered used. When the addresses are used, a more specific inetnummust be registered.
  • LEGACY: This indicates the Internet number resource was obtained prior to or otherwise outside the current system of hierarchical distribution (by allocation or assignment) through the Regional Internet Registries.
  • ASSIGNED PA: This address space has been assigned from. The registry
    will make the necessary changes to the zone, and update the net-
    work 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 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 availa-
    bility 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 domain at least
    once per working day.

    Example domain object to request a block delegation

    descr: Pan European Organisations class C block
    admin-c: Daniel Karrenberg
    tech-c: Marten Terpstra
    zone-c: Marten Terpstra
    changed: [email protected] 930319
    source: RIPE

    Procedures for the delegation of individual network zones by the

    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
    to the issuing LIR infrastructure or an End User for use with services provided by the issuing LIR. It cannot be kept when terminating services provided by the LIR.AGGREGATED-BY-LIR: This address space 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 ad-
    dress mapping, for all delegated networks a good set of secon-
    daries 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 re-
    verse zone for this network.

    3. If a network has or is going to have any external connectivi-
    ty, 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 net-
    works 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
    should be directed to <[email protected]>.

    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.

    to different parts of the issuing LIR infrastructure or to End Users for use with services provided by the issuing LIR. The purpose and the contact details must be consistent throughout the whole assignment. It cannot be kept when terminating services provided by the LIR.
  • ASSIGNED PI: This address space has been assigned to an End User for a specific purpose. It cannot be used to make further assignments to other parties.
  • ASSIGNED ANYCAST: This address space has been assigned for use in TLD anycast networks. It cannot be kept when no longer used for TLD anycast services.
  • The creation of an inetnum object with a status of "ASSIGNED PA" or "ASSIGNED PI" is only possible if there is no less specific or more specific inetnum object with an "ASSIGNED" status.

    Address space without an explicit type in the "status:" attribute is assumed to be PI. LIRs must clearly mark all new assignments in the RIPE Database with either "PA" or "PI" as appropriate.

    In the past, some LIRs assigned address space that was de facto aggregated but not formally PA because there were no clear contractual arrangements for termination of the assignment. LIRs must ask leaving customers to voluntarily release this address space upon termination of service. Where possible, LIRs should work to make contractual arrangements to convert PI addresses into PA addresses.

    The RIPE NCC no longer allocates or assigns PI address space, except for assignments to Internet Exchange Points as described in section 6.1.

    8.0 LIR Audit

    The RIPE community asked the RIPE NCC to audit LIR operations and ensure consistent and fair implementation of the community's policies. Details of this activity are described in the RIPE Document "RIPE NCC Audit Activity" found at: Link:

    9.0 Closing an LIR by the RIPE NCC

    The RIPE NCC may close an LIR for any of the following reasons:

    • the LIR does not pay money owed to the RIPE NCC
    • the LIR cannot be contacted by the RIPE NCC for a significant period of time
    • the LIR consistently violates the RIPE community's policies

    The RIPE NCC takes on responsibility for address space held by closing LIRs.