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What is the American Registry for Internet Numbers (ARIN)?
ARIN is the Regional Internet Registry (RIR) for the United States, Canada, and many Caribbean and North Atlantic islands. It is a nonprofit, member-based organization that allocates and administers Internet number resources — IPv4 and IPv6 addresses and Autonomous System Numbers (ASNs) — and maintains the public registry records that say who holds them.
If you need IP addresses or an ASN for a network you operate, ARIN is the organization you request them from in its region. Its site covers that whole lifecycle: getting started and managing an ARIN account, requesting addresses or ASNs, transferring resources between parties, reporting reassignments, and returning or revoking resources. It also publishes fee and billing information, including a fee schedule and payment options.
Beyond allocation, ARIN hosts registry and security services that network operators use directly:
- Whois for looking up resource holders, plus historical Whois data and bulk data
- RPKI and the Internet Routing Registry (IRR) for routing security
- Reverse DNS and DNSSEC support
- Reg-RWS for automating record management
- Tools such as a CIDR calculator and an operational test environment
Policy is a major part of the site. ARIN's Number Resource Policy Manual, the Policy Development Process, draft and recommended policies, and public policy and members meetings are all documented, and community input runs through mailing lists, consultations, and elections.
Who it's for: network engineers and admins at ISPs, enterprises, hosting providers, and universities; legal and compliance staff handling transfers; and community members who follow or propose numbering policy.
Practical next step: if you're unsure whether you qualify for a new allocation or should pursue a transfer instead, start with the "Get Started" and IPv4 addressing options pages, then check the fee schedule before filing a request so there are no billing surprises. For policy questions, the manual and the Policy Development Process pages are the authoritative references.
Related organizations in other regions include RIPE NCC, APNIC, and LACNIC; the global coordination body is Number Resource Organization.
How do I request IP addresses or ASNs from ARIN?
To request IP addresses or Autonomous System Numbers (ASNs) from ARIN, you begin by creating or accessing an ARIN Online account, then submitting a request through that account. ARIN is the nonprofit registry that administers these resources for the United States, Canada, and parts of the Caribbean, so the process is administrative rather than a simple purchase: you typically need to justify the need for the resources before they are assigned.
The basic path
- Get an ARIN Online account. An account is the entry point for requesting and managing resources.
- Choose what you need. IP addresses (IPv4 or IPv6) and ASNs are separate request types, and the requirements differ.
- Submit the request and supporting justification. For addresses, this usually means documenting how many you need and why, based on your network plan. For an ASN, you generally need to show a routing need, such as a multi-homed network.
- Respond to any follow-up. ARIN may ask for clarification or additional detail before approving.
- Manage the resources afterward. Once issued, records are maintained through ARIN Online, including reassignments and transfers.
IPv4 versus IPv6 versus ASN
| Request type | Typical situation | Practical note |
|---|---|---|
| IPv6 addresses | New or growing networks | Generally the most straightforward large allocation; designed for long-term growth |
| IPv4 addresses | Networks that still need IPv4 | Availability is limited, so requests face closer scrutiny and may involve waitlists or transfers |
| ASN | Networks that need to exchange routing with other networks | Usually tied to a demonstrated routing need rather than address count alone |
A concrete scenario
Suppose you run a small ISP launching service in two cities. You would create an ARIN Online account, request an ASN if you plan to peer with other networks, and request IPv6 space sized to your subscriber growth. If you also need IPv4, expect to justify each block carefully, because the free pool is largely exhausted and much of the remaining supply moves through transfers between organizations.
Useful next step
Start in ARIN Online and read the "Get Started" and "Requesting IP Addresses or ASNs" sections before filling anything out, since the justification questions shape your whole application. If you are weighing whether to request directly or acquire space through a transfer, compare the timeline and effort of each; ARIN's transfer documentation covers that route. The registry's own materials at American Registry for Internet Numbers are the authoritative source for current forms and requirements.
If you are unsure whether you qualify, the deciding factor is usually documented need: address requests hinge on your network's growth plan, and ASN requests hinge on a routing requirement. Gather that evidence first, and the rest of the process becomes mostly a matter of completing the forms accurately.
What are the fees and billing options for ARIN resources?
ARIN charges for the right to register and hold Internet number resources (IPv4 and IPv6 addresses and Autonomous System Numbers) in its region, and it separates the fee schedule from how you actually pay. The organization publishes a Fee Schedule that sets the amounts, and a separate How Billing Works page that explains invoices, cycles, and payment mechanics.
What you are paying for
ARIN's fees are generally tied to maintaining registrations and service categories rather than to one-time purchases of addresses. The site groups billing information under:
- Fee Schedule — the published fee amounts and categories.
- Premier Support Plan (PSP) — an optional enhanced-support tier.
- Make a Payment / Pay Now — the payment entry points.
- Resource Revocation, Returns, and Reinstatement — what happens to billing when resources change hands or lapse.
Because ARIN is member-based and nonprofit, fees also relate to membership status. Check the current Fee Schedule directly for exact figures, since these change over time and this summary deliberately avoids quoting numbers.
Billing options in practice
The practical flow is: you hold or request resources, ARIN issues an invoice on a billing cycle, and you pay through ARIN Online. The key decision points are:
| Situation | What to check |
|---|---|
| Requesting new IPv4/IPv6 or an ASN | Whether a fee applies at approval and how it recurs |
| Transferring resources | Whether fees follow the resource or the recipient |
| Returning or revoking resources | Effect on ongoing invoices |
| Wanting faster support | Whether PSP is worth the added cost |
A concrete scenario
Suppose a small ISP in ARIN's region obtains a block of IPv6 addresses and an ASN. It should expect recurring registration fees rather than a single purchase, an invoice tied to its ARIN Online account, and a payment path through the Make a Payment page. If it later transfers part of its IPv4 space, the billing picture changes, which is why the revocation/returns page matters as much as the fee schedule.
Next step: open the Fee Schedule for current amounts, then read How Billing Works to understand your invoice cycle before requesting resources.
How can I transfer IP addresses or ASNs to another organization?
To transfer IP addresses or ASNs to another organization, you request the transfer through ARIN's registry process rather than simply handing over the numbers. ARIN administers these resources in its region, so the transfer must be recorded in the registry to be valid.
American Registry for Internet Numbers
How the process generally works
- The current holder (or the recipient) initiates a transfer request in their ARIN account.
- The recipient organization typically needs its own ARIN account and must meet eligibility requirements, including demonstrating justified need for the resources.
- ARIN reviews the request, and once approved, updates the registry records to reflect the new holder.
- Both parties should confirm whether the transfer is within the ARIN region or involves another Regional Internet Registry, since inter-RIR transfers have additional requirements.
Practical steps
- Confirm the resources are eligible for transfer and not under revocation or hold.
- Create or log in to an ARIN Online account for the organization receiving the resources.
- Submit the transfer request and provide any supporting documentation ARIN requests.
- Coordinate with the other organization so both sides agree on the resources and terms.
- After approval, verify the updated records in Whois.
Trade-offs and cautions
- Transfers can take time because of review and documentation, so plan for delays.
- If you need help with a complex or inter-RIR transfer, ARIN offers support options such as a Premier Support Plan and instructional webinars.
- For legal or contractual terms between buyer and seller, consult your own advisors; ARIN's role is registry administration, not brokering the deal.
A useful next step is to check the "Transferring IP Addresses & ASNs" section of ARIN's site and open a transfer request in your ARIN Online account.
What is RPKI and how does it improve routing security?
RPKI (Resource Public Key Infrastructure) is a cryptographic system that lets the legitimate holder of an IP address block or Autonomous System Number (ASN) publish a signed statement, called a Route Origin Authorization (ROA), saying which ASNs are allowed to originate their routes. Networks that validate these statements can reject or downgrade routes that don't match, which reduces accidental misconfigurations and makes prefix hijacking harder.
American Registry for Internet Numbers lists RPKI under its Routing Security services, alongside the Internet Routing Registry (IRR) and DNSSEC, and provides tools such as the Operational Test and Evaluation (OT&E) environment for testing before production changes.
What RPKI actually does
- Creates verifiable claims. A ROA ties a prefix to an authorized origin ASN and a maximum prefix length.
- Enables validation. Validators fetch the signed data and compare it against BGP announcements, labeling routes as valid, invalid or not found.
- Informs routing decisions. Operators choose how strictly to act on those labels, from monitoring to dropping invalid routes.
What it does not do
RPKI secures the origin of a route, not the full path. It does not replace IRR-based filtering, prefix-list hygiene, or RPKI's companion for path validation, BGPsec. It also depends on operators actually publishing ROAs and validating them; partial adoption limits the benefit.
A concrete scenario
Suppose your organization holds 203.0.113.0/24 and announces it from AS64496. You publish a ROA naming AS64496 as the only authorized origin. If a misconfigured router elsewhere announces the same prefix from a different ASN, validating networks can flag that announcement as invalid and filter it, so your users keep reaching your services.
Practical next steps
- Confirm your registry's RPKI interface and create ROAs for your prefixes, matching the origin ASN and maximum length you actually announce.
- Run a validator in monitoring mode first; check how many of your own and your peers' routes would be marked invalid.
- Coordinate with upstreams and customers before enforcing drops, since a wrong ROA can take legitimate routes offline.
- Review ROAs after any renumbering, ASN change or transfer.
Deciding how far to go
| Approach | Effort | Main benefit | Main risk |
|---|---|---|---|
| Publish ROAs only | Low | Protects your prefixes from unauthorized origination | Incorrect ROA can break your own reachability |
| Validate in monitoring mode | Low | Visibility into invalid routes | No protection until you act |
| Validate and filter | Medium–high | Blocks hijacks and misconfigurations | False positives if ROAs are stale or wrong |
For most networks, publishing ROAs and validating in monitoring mode is a sensible starting point; enforcement follows once data quality is proven.
How can I participate in ARIN's policy development process?
You participate in ARIN's policy development process through the Policy Development Process (PDP), which the organization lists under its Policy & Participation section. The PDP is the formal channel through which the community proposes, debates, and advances changes to the Number Resource Policy Manual (NRPM), the document that governs how ARIN manages Internet number resources.
Where input happens
- Policy proposals: Anyone can submit a proposal to change the NRPM. Proposals enter the process and are published for community review.
- Mailing lists: ARIN hosts public mailing lists where proposals are discussed and refined; this is where most substantive debate occurs.
- Public Policy and Members Meetings: Held in person and remotely, these meetings include policy discussions and are a key venue for weighing in.
- Consultations & Suggestions: A channel for community feedback to ARIN outside the formal proposal track.
- Draft and Recommended Draft Policies: Once a proposal gains support, it moves through draft stages, each with its own comment period.
How the process typically flows
- Submit a proposal or comment on one already filed.
- Discuss it on the mailing list and at meetings; the Advisory Council shepherds the proposal.
- The Council recommends adoption, remand, or abandonment.
- The Board of Trustees makes the final decision, and adopted policy is incorporated into the NRPM.
Practical starting point
If you have a specific change in mind, read the NRPM first to see whether your idea is already addressed, then check the current Draft and Recommended Draft Policies to avoid duplicating an active proposal. If you mainly want to react to others' ideas, subscribe to the public mailing list and attend the next Public Policy and Members Meeting — participation does not require ARIN membership, though members also vote in Board and Advisory Council elections.
For background on how policy is set and who does the setting, the Number Resource Policy Manual and the PDP description are both published on ARIN. If you are comparing how regional internet registries handle policy input, the other RIRs follow similar open processes, but ARIN's own PDP documents are the authoritative source for participating in ARIN's.
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