# Prefix Advertisement

Published articles for Prefix Advertisement.

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## The Third App from J2sw: Prefix Advertisement Checker

DevFeed: [The Third App from J2sw: Prefix Advertisement Checker](<https://devfeed.tech/articles/the-third-app-from-j2sw-prefix-advertisement-checker-40188.md>)

Original publisher: [Read original article](<https://blog.j2sw.com/resources/prefix-advertisement-checker/>)

Author: j2sw

Published: 2026-07-31T12:17:00Z

Content type: tutorial

Language: en

Sources: [Justin Wilson (j2sw)](<https://devfeed.tech/sources/justin-wilson-j2sw.md>)

Topics: [BGP](<https://devfeed.tech/topics/bgp.md>), [networking](<https://devfeed.tech/topics/networking.md>), [App](<https://devfeed.tech/topics/app.md>), [Cisco](<https://devfeed.tech/topics/cisco.md>), [MikroTik](<https://devfeed.tech/topics/mikrotik.md>)

Tags: [application](<https://devfeed.tech/tags/application.md>), [bgp](<https://devfeed.tech/tags/bgp.md>), [irr](<https://devfeed.tech/tags/irr.md>), [j2-networks](<https://devfeed.tech/tags/j2-networks.md>), [j2-updates](<https://devfeed.tech/tags/j2-updates.md>), [network-engineering-resources](<https://devfeed.tech/tags/network-engineering-resources.md>), [network-tools](<https://devfeed.tech/tags/network-tools.md>), [network-troubleshooting](<https://devfeed.tech/tags/network-troubleshooting.md>), [prefix-advertisement](<https://devfeed.tech/tags/prefix-advertisement.md>), [ripe-ris](<https://devfeed.tech/tags/ripe-ris.md>), [roa](<https://devfeed.tech/tags/roa.md>), [routing](<https://devfeed.tech/tags/routing.md>), [routing-policy](<https://devfeed.tech/tags/routing-policy.md>), [rpki](<https://devfeed.tech/tags/rpki.md>), [visibility](<https://devfeed.tech/tags/visibility.md>)

### AI overview

This article describes the J2SW Prefix Advertisement Checker, an application that evaluates an exact IPv4 or IPv6 prefix using live BGP data. It reports observed origin ASNs from RIPE RIS collectors, collector visibility, RPKI/ROA status, and matching IRR route objects, with an optional expected origin ASN for comparison.

### Source excerpt

A prefix can appear in the global BGP table and still have a routing problem. The route may originate from the wrong ASN. Its ROA may also authorize a shorter prefix but reject the advertised prefix length. Checking each part normally means pulling data from several routing tools. The J2SW Prefix Advertisement Checker, my 3rd ... Read more The post The Third App from J2sw: Prefix Advertisement Checker appeared first on Justin Wilson (j2sw).