AS39961 San Francisco Department of Telecommunications and Information Services

CCSF - San Francisco Department of Telecommunications and Information Services · registered in the United States

IPv4 addresses58,36816 prefixes · 0.002% of announced IPv4

Rank in United States#1,416largest network in US by IPv4 space, of 18,338 · <0.01% of US

Rank worldwide#3,695of 79,396 networks with IPv4

IPv6noneno IPv6 routes announced

CountryUnited States18,679 ASNs registered there

Open AS39961 in ASN lookup Look up an IP in this network (208.121.0.1) All networks in United States

IPv4 prefixes

All 16 prefixes, in address order.

208.121.0.0/23
208.121.5.0/24
208.121.6.0/24
208.121.32.0/19
208.121.64.0/18
208.121.128.0/18
208.121.192.0/21
208.121.200.0/22
208.121.204.0/22
208.121.208.0/20
208.121.224.0/22
208.121.228.0/23
208.121.230.0/24
208.121.231.0/24
208.121.232.0/21
208.121.240.0/20

Similar-sized networks in United States

ASNNameIPv4 addresses

AS12097#1413 MASSCOM - Massillon Cable Communications58,624

AS27026#1414 NETWORKMARYLAND - networkMaryland58,624

AS11231#1415 GETTYSBURG-DOM - GETTYSBURG COLLEGE58,368

AS4927#1417 IMPU - Aseva LLC58,112

AS5663#1418 EDCNET - Department of Interior United States Geological Survey58,112

AS14956#1419 ROUTERHOSTING - RouterHosting LLC58,110

IP-to-ASN data: iptoasn.com (public domain). Snapshot downloaded 2026-11-11, refreshed daily. Ranges are what each network announces in BGP, not registry allocations. Data sources