An Autonomous System Number (ASN) uniquely identifies a collection of routed IP prefixes managed by one organization. It supports policy‑based routing across the global Internet, allowing networks to announce reachability, peer with others, and influence traffic paths. Understanding ASN properties helps engineers audit routing, confirm ownership, and troubleshoot connectivity anomalies.
The lookup interface lets you enter an ASN such as 15169 or any public IP address. A reactive engine retrieves public registry data, converts IPs to ASNs when needed, and summarizes key attributes in real time. Tabs reveal holder details, announced prefixes, upstream and downstream peers, and a color‑coded JSON view ready for export.
Use this tool during incident response to confirm whether a suspicious IP belongs to your network or an external provider; verify results with authoritative sources before making routing changes.
Technical Details:
The page runs entirely in your browser. A lightweight reactive layer calls public registry endpoints through a proxy, then binds the returned JSON to visible components. No credentials are required, and no input or result is stored server‑side. Automatic error handling rolls back the UI and invites a retry when requests fail.
Data objects flow from fetch helpers to computed properties, so every badge, table cell, or tab updates instantly. Clipboard helpers use the modern API with a textarea fallback for older browsers, and downloads rely on `Blob` URLs that vanish after use.
Real‑Time Conversion
Enter an IP address to fetch its ASN automatically before querying detailed records.
Summary Banner
A prominent banner highlights the ASN, holder, country, and status for quick scanning.
Tabbed Explorer
Switch between Info, Prefixes, Peers, and JSON without additional network calls.
Clipboard Actions
Copy the ASN or the full JSON payload with a single click and immediate visual feedback.
JSON Export
Download a neatly formatted `.json` file named after the ASN for archival or scripting.
Resilient Error Handling
If any fetch fails, the interface shows a concise alert and re‑enables the Lookup button.
Step‑by‑Step Guide:
Follow these steps to retrieve and explore ASN data.
- Type an ASN or IP into the ASN or IP: field, then press Enter.
- Click Lookup if automatic submission is disabled.
- Review the banner for holder, country, and status confirmation.
- Select Prefixes, Peers, or JSON from the tab bar to change views.
- Click Copy ASN or Copy JSON for clipboard copies.
- Choose Download JSON to save the response locally.
FAQ:
Common questions appear below. Expand an item to read the answer.
What sources power the results?
The tool queries RIPE Stat endpoints for ASN overview, prefixes, peer counts, and neighbours. IP addresses first pass through a public IP‑to‑ASN service.
Can I enter an IP address?
Yes. The engine converts IPv4 or IPv6 addresses to the corresponding ASN before fetching registry data.
Is my data stored?
No. Inputs and results live only in your browser. Nothing is sent to any server beyond the public registry APIs.
Why do peers show zero?
Some ASNs have no visible upstream or downstream peers in the current routing dataset, or the registry has incomplete information.
How accurate is the country field?
Country codes reflect registry records and may differ from physical router locations, especially for global networks.
Troubleshooting:
Resolve common issues quickly.
- Lookup button stays disabled – Clear the input field, type again, and ensure at least one character is present.
- “Lookup failed.” alert – Registry API may be unreachable. Wait a minute and retry.
- Peers tab empty – The ASN might not have recorded neighbours in the selected dataset.
- Copy buttons do nothing – Your browser may block clipboard access; allow permissions or use the JSON tab to select manually.
- Downloaded file is empty – Ensure data loaded before clicking Download JSON; the banner must be visible first.
Advanced Tips:
Work faster with these expert suggestions.
- Bookmark queries by copying the current URL; parameters persist through query strings.
- Open multiple tabs with different ASNs for side‑by‑side comparison.
- Pipe exported JSON into command‑line tools to automate network audits.
- Use browser dev‑tools to watch the raw API responses in the Network panel.
- Inspect peer types to infer transit versus downstream relationships quickly.
Glossary:
Key terms used throughout the application.
- ASN
- Unique identifier for an autonomous system.
- Prefix
- IP block announced by an ASN.
- Peer
- Another ASN exchanging routes directly.
- Upstream
- Provider that forwards traffic toward the Internet.
- Downstream
- Customer network receiving connectivity.