Instantly check if an Autonomous System Number (ASN) is public or private. Free, fast BGP ASN validation tool for network engineers and IT professionals.
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Autonomous System Number (ASN) Range Validator
Overview
A high-performance, browser-based utility designed for network engineers and system administrators to instantly verify whether a given ASN falls into the Public or Private range. This tool adheres to RFC 6996 standards.
Features
- Instant Validation: Real-time checking as the user types.
- Dual Range Support: Fully supports both 16-bit and 32-bit ASN formats.
- Categorical Feedback: Clear visual indicators for "Public", "Private", "Reserved", and "Invalid" inputs.
- Visual Explanations: Dynamic text generation explaining why an ASN belongs to a specific category (e.g., citing the specific RFC range).
- Bulk Awareness: While the core is single-input, the UI is optimized for quick, repetitive checks without page reloads.
UI/UX Layout
- Header: A clean, minimal header containing the app name and a brief description.
- Input Section: A prominent, centered text input field styled with a subtle border and shadow, optimized for numerical entry. Includes a clear button for rapid clearing.
- Result Display: A dynamic "Result Card" that changes color based on the status (Green for Public, Amber for Private, Blue for Reserved, Red for Invalid).
- Info Section: A compact "Reference Table" below the main tool that lists the RFC ranges for 16-bit and 32-bit ASNs for quick user reference.
Color Palette & Styling
- Primary: Crisp white background (#FFFFFF) with neutral grey text (#374151).
- Accent: Soft blue (#2563EB) for interactive elements (buttons, focus states).
- Semantic Colors:
- Success (Public): Green (#059669) with a light green background.
- Warning (Private): Amber (#D97706) with a light amber background.
- Danger (Invalid/Reserved): Red (#DC2626) with a light red background.
- Transitions: All UI state changes utilize
transition: all 0.3s ease-in-outfor a smooth, high-end SaaS feel.
Technical Implementation Directives
- Architecture: The entire application must be contained in a single
index.htmlfile. - Styling: Use a CDN-linked Tailwind CSS file for rapid styling, or standard CSS in a
<style>block if preferred. - No Storage: Strictly follow the constraint to avoid
localStorageorsessionStoragedue to sandboxed iframe execution. - Logic: Handle all validation using pure Vanilla JavaScript functions.
- Responsiveness: Use CSS Grid/Flexbox to ensure the input card centers perfectly on mobile and desktop screens.
- Security: Ensure no external requests are triggered by user input. All logic must be local.
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Frequently Asked Questions
Everything you need to know about using this application.
What is the difference between a public and a private Autonomous System Number (ASN)?
An Autonomous System Number (ASN) is a unique identifier used in Border Gateway Protocol (BGP) routing to identify a group of IP prefixes under a single network policy. Public ASNs are assigned by Regional Internet Registries (RIRs) and are globally unique, allowing routes to be propagated across the public internet without conflict. Private ASNs, on the other hand, are reserved for internal use within a single network or between networks using private peering agreements. These numbers are not globally unique and must not be advertised to the public internet, as they would conflict with other networks using the same private numbers.
How does this tool identify if an ASN is private?
This tool validates your input against the standard ranges defined in RFC 6996 and RFC 5396. The 16-bit private range spans 64512 through 65534, while the 32-bit private range spans 4200000000 through 4294967294. Any number input into the tool is checked against these specific integer ranges to provide an immediate classification. In addition to identifying the range, the tool also flags reserved ASN values, such as 0 or 65535, which have specific technical meanings in BGP configuration and cannot be used for standard routing or peering purposes.
Can I use private ASNs on the public internet?
No, you absolutely cannot use private ASNs on the public internet. If you leak routes originating from a private ASN to the public internet, those routes will be dropped or ignored by upstream providers, causing significant routing failures. BGP best practices require all networks that participate in public peering to obtain a registered public ASN from their regional registry. Private ASNs are intended solely for specific, contained scenarios, such as data center internal infrastructure or private peering sessions where routes are stripped and replaced with a valid public ASN before exiting the administrative domain. Always consult with your upstream transit provider before configuring BGP peering.
Does this tool store my network configuration or ASN data?
No, this application is strictly client-side. It does not possess any server-side database, backend API, or local storage mechanism to save your input. Every calculation happens in the memory of your browser, and no data is transmitted to external servers. Because this tool is built for security and privacy, it does not use cookies, localStorage, or session storage. Once you close your browser tab or refresh the page, all information related to your previous validation checks is completely wiped from your device's memory.
