{"classifier_version":"1.4.0","documentation":"https://rirtracker.com/api/","disclaimer":"This site independently analyzes publicly available Internet number-resource records. It is not affiliated with or endorsed by ARIN, the RIPE NCC, APNIC, LACNIC, AFRINIC, the Number Resource Organization (NRO), or any other Regional Internet Registry. Classifications and hold-expiration dates are evidence-based interpretations and do not constitute confirmation that a resource is available for issuance or transfer.","resource":"51.0.0.0/8","resource_type":"ipv4","page":"https://rirtracker.com/ip/51.0.0.0-51.255.255.255/","statistics_now":{"registry":"ARIN","status":"allocated (dated 2019-01-10), allocated (dated 2019-03-11), allocated (dated 2019-09-03), allocated (dated 2020-03-31)"},"current_holder":{"rir":null,"org":null,"how":null},"rdap_snapshots":[],"transfers":[{"id":116255,"date":"2025-11-11T19:00:00Z","type":"RESOURCE_TRANSFER","source_rir":"RIPE NCC","recipient_rir":"RIPE NCC","source_org":"A100 ROW Inc","recipient_org":"Amazon Data Services European Sovereign Cloud GmbH","range":"51.0.0.0/19","log":"RIPE NCC"},{"id":116256,"date":"2025-11-11T19:00:00Z","type":"RESOURCE_TRANSFER","source_rir":"RIPE NCC","recipient_rir":"RIPE NCC","source_org":"A100 ROW Inc","recipient_org":"Amazon Data Services European Sovereign Cloud GmbH","range":"51.72.0.0/15","log":"RIPE NCC"},{"id":112922,"date":"2025-05-14T19:00:00Z","type":"RESOURCE_TRANSFER","source_rir":"RIPE NCC","recipient_rir":"RIPE NCC","source_org":"SHELLNET S.P.A.","recipient_org":"Opnet Srl","range":"51.179.0.0/17","log":"RIPE NCC"},{"id":69491,"date":"2020-03-31T19:00:00Z","type":"RESOURCE_TRANSFER","source_rir":"RIPE NCC","recipient_rir":"ARIN","source_org":"OVH SAS","recipient_org":null,"range":"51.222.0.0/16","log":"RIPE NCC"},{"id":20350,"date":"2020-03-31T14:22:04Z","type":"RESOURCE_TRANSFER","source_rir":"RIPE NCC","recipient_rir":"ARIN","source_org":"OVH SAS","recipient_org":"OVH Hosting, Inc.","range":"51.222.0.0/16","log":"ARIN"},{"id":66893,"date":"2019-11-14T19:00:00Z","type":"RESOURCE_TRANSFER","source_rir":"RIPE NCC","recipient_rir":"APNIC","source_org":"Equinix Services Limited","recipient_org":null,"range":"51.162.0.0/17","log":"RIPE NCC"},{"id":126338,"date":"2019-11-14T07:15:56Z","type":"RESOURCE_TRANSFER","source_rir":"RIPE NCC","recipient_rir":"APNIC","source_org":"ORG-IA69-RIPE","recipient_org":"EQUINIX (AUSTRALIA) ENTERPRISES PTY LIMITED","range":"51.162.0.0/17","log":"APNIC"},{"id":65793,"date":"2019-09-03T19:00:00Z","type":"RESOURCE_TRANSFER","source_rir":"RIPE NCC","recipient_rir":"ARIN","source_org":"OVH SAS","recipient_org":null,"range":"51.161.0.0/16","log":"RIPE NCC"},{"id":18747,"date":"2019-09-03T14:07:04Z","type":"RESOURCE_TRANSFER","source_rir":"RIPE NCC","recipient_rir":"ARIN","source_org":"OVH SAS","recipient_org":"OVH Hosting, Inc.","range":"51.161.0.0/16","log":"ARIN"},{"id":63013,"date":"2019-03-11T19:00:00Z","type":"RESOURCE_TRANSFER","source_rir":"RIPE NCC","recipient_rir":"ARIN","source_org":"OVH SAS","recipient_org":null,"range":"51.81.0.0/16","log":"RIPE NCC"},{"id":17088,"date":"2019-03-11T15:03:07Z","type":"RESOURCE_TRANSFER","source_rir":"RIPE NCC","recipient_rir":"ARIN","source_org":"OVH SAS","recipient_org":"OVH US LLC","range":"51.81.0.0/16","log":"ARIN"},{"id":62056,"date":"2019-01-10T19:00:00Z","type":"RESOURCE_TRANSFER","source_rir":"RIPE NCC","recipient_rir":"ARIN","source_org":"OVH SAS","recipient_org":null,"range":"51.79.0.0/16","log":"RIPE NCC"},{"id":16787,"date":"2019-01-10T15:41:33Z","type":"RESOURCE_TRANSFER","source_rir":"RIPE NCC","recipient_rir":"ARIN","source_org":"OVH SAS","recipient_org":"OVH Hosting, Inc.","range":"51.79.0.0/16","log":"ARIN"},{"id":48182,"date":"2015-05-29T19:00:00Z","type":"RESOURCE_TRANSFER","source_rir":"RIPE NCC","recipient_rir":"RIPE NCC","source_org":"S.C. GVM SISTEM 2003 S.R.L.","recipient_org":"Saudi Telecom Company JSC","range":"51.211.0.0/16","log":"RIPE NCC"},{"id":48183,"date":"2015-05-29T19:00:00Z","type":"RESOURCE_TRANSFER","source_rir":"RIPE NCC","recipient_rir":"RIPE NCC","source_org":"S.C. GVM SISTEM 2003 S.R.L.","recipient_org":"Saudi Telecom Company JSC","range":"51.218.0.0/16","log":"RIPE NCC"},{"id":48184,"date":"2015-05-29T19:00:00Z","type":"RESOURCE_TRANSFER","source_rir":"RIPE NCC","recipient_rir":"RIPE NCC","source_org":"S.C. GVM SISTEM 2003 S.R.L.","recipient_org":"Saudi Telecom Company JSC","range":"51.223.0.0/16","log":"RIPE NCC"},{"id":48185,"date":"2015-05-29T19:00:00Z","type":"RESOURCE_TRANSFER","source_rir":"RIPE NCC","recipient_rir":"RIPE NCC","source_org":"S.C. GVM SISTEM 2003 S.R.L.","recipient_org":"Saudi Telecom Company JSC","range":"51.235.0.0/16","log":"RIPE NCC"},{"id":48186,"date":"2015-05-29T19:00:00Z","type":"RESOURCE_TRANSFER","source_rir":"RIPE NCC","recipient_rir":"RIPE NCC","source_org":"S.C. GVM SISTEM 2003 S.R.L.","recipient_org":"Saudi Telecom Company JSC","range":"51.252.0.0/15","log":"RIPE NCC"}],"events":[{"event_id":"fbf1217ea39a2531","registry":"ARIN","report_date":"2009-02-26","source":"statistics","raw_action":"NOT_IN_ARIN_ISSUED","raw_line":null,"resource_type":"ipv4","resource":"51.0.0.0/8","start":"51.0.0.0","end":"51.255.255.255","classification":"REMOVED_REASON_UNKNOWN","classification_label":"Removed (return, revocation or reclamation not publicly distinguishable)","confidence":"STRONG_INFERENCE","source_rir":null,"recipient_rir":null,"source_organization":null,"recipient_organization":null,"inventory_effect":"Possible future reissue candidate after hold","inventory_effect_code":"HOLD_CANDIDATE","provisional":false,"classifier_version":"1.4.0","classified_at":"2026-10-13T23:54:54+00:00","page":"https://rirtracker.com/ip/51.0.0.0-51.255.255.255/#e-fbf1217ea39a2531","report_page":"https://rirtracker.com/arin/reports/2009-02-26/","evidence_url":"https://rirtracker.com/api/v1/resources/ip/51.0.0.0-51.255.255.255.json","observed":"51.0.0.0/8 assigned on 2009-02-26, not listed on 2009-02-27","hold":{"hold_rule_source_url":"https://www.arin.net/resources/guide/request/#reissuing-returned-revoked-and-reclaimed-resources","hold_rule_days":60,"estimated_hold_end":"2009-04-27","availability_statement":"Possible reissue candidate after this date; not confirmed available"},"explanation":"Removed from active registration. ARIN-Issued didn't list this; the tracker found it by comparing ARIN's daily statistics. ARIN's statistics show it assigned (dated 1991-09-16) on 2009-02-25 and not issued on 2009-02-27. (Until 2013-03-05, ARIN's statistics list only what's issued.) Public sources do not distinguish a voluntary return, revocation, or reclamation. ARIN holds returned, revoked and reclaimed IPv4 space for 60 days before reissuing it, so the estimated hold end is 2009-04-27. This does not confirm availability.","evidence":[{"type":"statistics_diff","url":"https://ftp.arin.net/pub/stats/arin/archive/2009/delegated-arin-20090227.gz","retrieved_at":"2026-10-12T18:47:03+00:00","summary":"Not listed in ARIN-Issued; found by comparing ARIN's daily statistics: 51.0.0.0/8 assigned on 2009-02-26, not listed on 2009-02-27"},{"type":"delegated_before","url":"https://ftp.arin.net/pub/stats/arin/archive/2009/delegated-arin-20090225.gz","retrieved_at":"2026-10-12T18:46:56+00:00","summary":"ARIN delegated statistics 2009-02-25, before the report: assigned (dated 1991-09-16)"},{"type":"delegated_after","url":"https://ftp.arin.net/pub/stats/arin/archive/2009/delegated-arin-20090227.gz","retrieved_at":"2026-10-12T18:47:03+00:00","summary":"ARIN delegated statistics 2009-02-27, after the report: not issued"}]}],"classification_history":{"fbf1217ea39a2531":[{"raw_change_id":202334,"classification_code":"REMOVED_REASON_UNKNOWN","confidence":"STRONG_INFERENCE","classifier_version":"1.3.0","classified_at":"2026-10-13T04:10:07+00:00","current":0,"public_explanation":"Removed from active registration. ARIN-Issued didn't list this; the tracker found it by comparing ARIN's daily statistics. ARIN's statistics show it assigned (dated 1991-09-16) on 2009-02-25 and not issued on 2009-02-27. (Until 2013-03-05, ARIN's statistics list only what's issued.) Public sources do not distinguish a voluntary return, revocation, or reclamation. ARIN holds returned, revoked and reclaimed IPv4 space for 60 days before reissuing it, so the earliest estimated hold expiration is 2009-04-27. This does not confirm availability."},{"raw_change_id":202334,"classification_code":"REMOVED_REASON_UNKNOWN","confidence":"STRONG_INFERENCE","classifier_version":"1.3.1","classified_at":"2026-10-13T08:08:22+00:00","current":0,"public_explanation":"Removed from active registration. ARIN-Issued didn't list this; the tracker found it by comparing ARIN's daily statistics. ARIN's statistics show it assigned (dated 1991-09-16) on 2009-02-25 and not issued on 2009-02-27. (Until 2013-03-05, ARIN's statistics list only what's issued.) Public sources do not distinguish a voluntary return, revocation, or reclamation. ARIN holds returned, revoked and reclaimed IPv4 space for 60 days before reissuing it, so the earliest estimated hold expiration is 2009-04-27. This does not confirm availability."},{"raw_change_id":202334,"classification_code":"REMOVED_REASON_UNKNOWN","confidence":"STRONG_INFERENCE","classifier_version":"1.3.2","classified_at":"2026-10-13T14:51:18+00:00","current":0,"public_explanation":"Removed from active registration. ARIN-Issued didn't list this; the tracker found it by comparing ARIN's daily statistics. ARIN's statistics show it assigned (dated 1991-09-16) on 2009-02-25 and not issued on 2009-02-27. (Until 2013-03-05, ARIN's statistics list only what's issued.) Public sources do not distinguish a voluntary return, revocation, or reclamation. ARIN holds returned, revoked and reclaimed IPv4 space for 60 days before reissuing it, so the earliest estimated hold expiration is 2009-04-27. This does not confirm availability."},{"raw_change_id":202334,"classification_code":"REMOVED_REASON_UNKNOWN","confidence":"STRONG_INFERENCE","classifier_version":"1.4.0","classified_at":"2026-10-13T23:54:54+00:00","current":1,"public_explanation":"Removed from active registration. ARIN-Issued didn't list this; the tracker found it by comparing ARIN's daily statistics. ARIN's statistics show it assigned (dated 1991-09-16) on 2009-02-25 and not issued on 2009-02-27. (Until 2013-03-05, ARIN's statistics list only what's issued.) Public sources do not distinguish a voluntary return, revocation, or reclamation. ARIN holds returned, revoked and reclaimed IPv4 space for 60 days before reissuing it, so the estimated hold end is 2009-04-27. This does not confirm availability."}]},"arin_statistics_now":{"status":"allocated (dated 2019-01-10), allocated (dated 2019-03-11), allocated (dated 2019-09-03), allocated (dated 2020-03-31)"}}