ASN Overview
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{{ overview.holder }} {{ overview.country }} {{ overview.status }} Items: 1 Valid
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Field Value Copy
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Prefix IP Version Copy
{{ p.prefix }} {{ p.ip_version }}
No prefixes.
ASN Name Type Copy
{{ pr.asn }} {{ pr.name }} {{ pr.type }}
No peers.
 

            


        


        
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                            Categories:
                                                            
                                    IP Tools
                                
                                ,                                                             
                                    Networking
                                
                                                                                    

                        

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Autonomous System Numbers (ASNs) are identifiers for routing domains that publish policy through the Border Gateway Protocol. An ASN names a network that advertises routes on the wider internet, sometimes called an autonomous system or just an AS. Operators often search autonomous system lookup to confirm who originates specific prefixes and how those announcements relate to neighboring networks during troubleshooting.

  
You enter an AS number or a single IP address and receive a compact dossier that maps the organization and country. It lists status dates, announced prefixes and nearby autonomous systems, giving you a snapshot of routing presence. If you start from an IP it is first resolved to its origin AS using connection data from a geolocation service.

  
For example, querying AS15169 returns the holder name plus IPv4 and IPv6 blocks such as 8.8.8.0/24 and several neighboring ASNs. You can scan the shortest prefix length to gauge aggregation and copy rows into tickets or runbooks for quick follow‑up. Treat contact addresses and external websites with care, and confirm routing with multiple sources before pushing changes.

  
When comparing networks focus on the direction of peering counts and whether the table includes native IPv6 space for current reachability. Use prefix sorting to spot discontiguous ranges, or filter neighbor type to examine left, right or uncertain relationships as modeled by the source data. Cross‑check dates before incident reports and change reviews during postmortems.






  
Technical Details:

  
The lookup resolves input to an origin ASN and aggregates routing and registry facts from multiple operator data sources. Core outputs are organization, country, status timestamps, prefix list, peer counts, neighboring ASNs, and selected RDAP contacts. Prefix statistics summarize IPv4 versus IPv6 and shortest or longest CIDR lengths. Sorting and filtering operate on the fetched lists only, never on hidden data. Processing is deterministic for identical upstream responses. Network requests use a short timeout and are cancelled when superseded by a new query. Supplemental metadata may include BGPView names, brief descriptions, looking glass references, and PeeringDB fields such as policy URL or IRR AS‑SET when available.


  
Processing pipeline:

  
    
    
  1. Parse input, trim whitespace, keep only the first nonempty line.
    2. 
    
  2. Detect IPv4 or IPv6 using patterns; treat any “::” as IPv6 shorthand.
    3. 
    
  3. If IP, query a geolocation service for its origin ASN.
    4. 
    
  4. If ASN, normalize by stripping a leading “AS” and validating digits.
    5. 
    
  5. Request RIPEstat overview, announced prefixes, peer counts, and neighbours.
    6. 
    
  6. Derive prefix and peer statistics; apply client‑side sorting and filtering.
    7. 
    
  7. Fetch RDAP autnum; extract contacts and last changed or last update dates.
    8. 
    
  8. Optionally load BGPView and PeeringDB details for organization and policy context.
    9. 
    
  9. Render tables and an exportable JSON payload; enable Copy and Download actions.
    10. 
    
  10. Abort requests after nine seconds and ignore out‑of‑order responses using a sequence id.
    11. 
  


  
Variables & parameters:

  

    

      
      
        

          Parameter
          Meaning
          Unit/Datatype
          Typical Range
          Sensitivity
          Notes
        

      
      
        

          asn
          AS number or IP input
          string
          “AS15169”, “15169”, “8.8.8.8”, IPv6 literal
          High
          Only the first nonempty line is processed.
        

        

          limit_prefixes
          Maximum prefixes to show
          integer
          0–10 000
          Medium
          0 shows all; applied after sorting.
        

        

          prefix_sort
          Sorting strategy for prefixes
          enum
          “”, “length”, “alpha”
          Low
          Length sorts by CIDR size; alpha is lexical.
        

        

          peer_type
          Neighbour type filter
          enum
          “”, “left”, “right”, “uncertain”
          Low
          Matches source‑provided relationship labels.
        

      
    

  


  
Validation & bounds extracted from code:

  

    

      
      
        

          Field
          Type
          Min
          Max
          Step/Pattern
          Error Text
          Placeholder
        

      
      
        

          ASN or IP
          text
          —
          —
          
            

              IPv4: ^(25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)\.(25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)\.(25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)\.(25[0-5]|2[0-4]\d|1\d\d|[1-9]?\d)$

              IPv6: ^(([0-9A-Fa-f]{1,4}:){1,7}[0-9A-Fa-f]{1,4}|(([0-9A-Fa-f]{1,4}:){1,7}:)|(::([0-9A-Fa-f]{1,4}:){0,6}[0-9A-Fa-f]{1,4}))$

              IPv6 also accepted if the string contains “::”.

              ASN normalize: ^\d{1,10}$ after removing a leading “AS”.
            

          		
          Enter an ASN or IP address. · Lookup failed.
          AS15169 or 8.8.8.8
        

        

          Limit prefixes
          number
          0
          —
          step 1
          —
          rows
        

        

          Prefix sort
          select
          —
          —
          [source order | length | alpha]
          —
          —
        

        

          Peer type
          select
          —
          —
          [all | left | right | uncertain]
          —
          —
        

      
    

  


  
I/O formats & encoding:

  

    

      
      
        

          Input
          Accepted Families
          Output
          Encoding/Precision
          Rounding
        

      
      
        

          Single string
          ASN (“ASn” or digits), IPv4, IPv6
          Tables (Info, Prefixes, Peers) and JSON
          Integers and strings; JSON keys: inputs, warnings, overview, peerInfo, prefixes, peers, rdap, bgpview, peeringdb
          Not applicable; values are discrete
        

      
    

  


  
Units, precision & rounding policy:

  
    
    
  • Counts and prefix lengths are integers in base 10.
    • 
    
  • No significant‑figure rounding is applied.
    • 
    
  • Decimal separators are not used in outputs.
    • 
    
  • Tie‑breaking does not apply because values are categorical or integral.
    • 
  


  
Networking & storage behavior:

  
    
    
  • External calls include ipwho.is for IP→ASN, RIPEstat data calls, RDAP autnum endpoints from regional registries, BGPView, and PeeringDB.
    • 
    
  • Requests are proxied through a CORS helper with a nine‑second timeout and abort on superseding queries.
    • 
    
  • No persistent storage is used; clipboard and file downloads occur locally.
    • 
  


  
Performance & complexity:

  
    
    
  • Parsing and JSON formatting are O(n) in input size.
    • 
    
  • Prefix sorting is O(m log m); filtering is O(m).
    • 
    
  • UI updates are incremental; large JSON blocks are streamed to the DOM as text.
    • 
  


  
Diagnostics & determinism:

  
    
    
  • Deterministic for identical upstream responses.
    • 
    
  • Surface errors: “Enter an ASN or IP address.” and “Lookup failed.”
    • 
    
  • Extra pasted lines are ignored in single‑item mode with a clear warning.
    • 
  


  
Security considerations:

  
    
    
  • Inputs are sent to third‑party services; do not paste secrets or internal ticket links.
    • 
    
  • Sanitize copied data before issuing commands or making firewall changes.
    • 
    
  • Verify RDAP contact legitimacy; avoid phishing by cross‑checking hostnames.
    • 
  


  
Worked example:

  

  
Assumptions & limitations:

  
    
    
  • Heads‑up Only the first pasted line is processed in this build.
    • 
    
  • Neighbour types reflect the source model; not all paths are symmetric.
    • 
    
  • Prefix statistics depend on upstream data freshness.
    • 
    
  • RDAP roles and emails may be missing or redacted by registry policy.
    • 
    
  • BGPView and PeeringDB records may not exist for every ASN.
    • 
    
  • Timeouts can suppress slow responses; re‑query to confirm.
    • 
  


  
Edge cases & error sources:

  
    
    
  • Ambiguous IPv6 forms or unusual compression.
    • 
    
  • Private or reserved IPv4 addresses.
    • 
    
  • Non‑digit characters after removing “AS”.
    • 
    
  • Very large result sets causing long tables.
    • 
    
  • Mismatched Unicode in RDAP vcardArray emails.
    • 
    
  • Out‑of‑order network responses, ignored by sequence control.
    • 
    
  • Aborted fetches due to short timeout.
    • 
    
  • Upstream schema changes altering key names.
    • 
  


  
Scientific & standards backing:

  
    
    
  • Border Gateway Protocol defines inter‑domain route exchange and policy.
    • 
    
  • Registration Data Access Protocol (RDAP) standardizes contact and registry data for number resources.
    • 
    
  • Autonomous System Number allocation and formatting follow global registry policies.
    • 
  


  
Privacy & compliance:

  
Requests originate from your browser to the listed services; no persistent server‑side storage is used by this page.






  
Step‑by‑Step Guide:

  
Use this sequence to identify a route’s owner, context, and neighbours.

  
    
    
  1. Enter AS number or IP address in the input box.
    2. 
    
  2. Press Enter or select Lookup to start the query.
    3. 
    
  3. Open the Info, Prefixes, or Peers tab to review results.
    4. 
    
  4. Use Advanced to sort prefixes or filter neighbour type.
    5. 
    
  5. Copy a row, or download CSV and JSON for evidence.
    6. 
  

  
Example: Input AS15169, then download AS15169_prefixes.csv for an audit note.

  
Warning Double‑check organization names and dates before changes.






  
FAQ:


  

    Is my data stored?
    
No persistent storage is used by this page; requests are dispatched from your browser to external data providers.

  


  

    How accurate are the results?
    
Results mirror upstream sources. Always corroborate critical findings with multiple registries or route views when preparing changes or incident reports.

  


  

    What inputs are supported?
    
ASNs with or without the “AS” prefix, IPv4 dotted‑decimal, and IPv6 textual forms. Only the first nonempty line is processed.

  


  

    Can I use it offline?
    
No. Network lookups require live access to operator and registry endpoints.

  


  

    Does it export data?
    
Yes. You can copy tables to the clipboard or download CSV files and a structured JSON payload for records.

  


  

    How do I check who owns 8.8.8.8?
    
Paste the IP, run Lookup, then read the organization in the Info tab. Review prefixes and neighbours for fuller routing context.

  


  

    Why do I see “left”, “right”, or “uncertain”?
    
Those are neighbour types supplied by the source model. They indicate inferred relationship direction and confidence, not contractual peering.

  






  
Troubleshooting:

  
    
    
  • Empty input: add an ASN or IP and try again.
    • 
    
  • No results: confirm the ASN is numeric after removing “AS”.
    • 
    
  • Timeouts: retry; some registries rate‑limit or respond slowly.
    • 
    
  • Missing contacts: RDAP roles may be absent for some records.
    • 
    
  • Huge tables: set Limit prefixes to a manageable number.
    • 
    
  • Unexpected peers: filter by neighbour type to narrow the list.
    • 
  

  





  
Advanced Tips:

  
    
    
  •  Prefer ASN input for precision; IP→ASN resolution can vary by vantage.
    • 
    
  •  Sort by length to spot overly specific announcements that may be traffic‑engineered.
    • 
    
  •  Compare shortest and longest prefix lengths to assess aggregation discipline.
    • 
    
  •  Use JSON export in change reviews to preserve evidence and parameter settings.
    • 
    
  •  Cross‑reference RDAP emails with corporate domains before outreach.
    • 
  






  
Glossary:

  

    
ASN

    
Numeric label identifying a routing domain that speaks BGP.


    
BGP

    
Inter‑domain routing protocol exchanging reachability and policy.


    
CIDR

    
Address aggregation method using prefix length, for IPv4 or IPv6.


    
RDAP

    
Standard interface for registry data, contacts, and events.


    
Prefix length

    
Slash notation showing how many leading bits define the network.


    
Neighbour

    
An adjacent AS observed or inferred by upstream data sources.


    
IRR AS‑SET

    
Routing policy object grouping prefixes or members for filtering.