204.100.0.0/16

Currently announced by AS18558 Riverside County Office of Education, in the routed prefix 204.100.0.0/16.

Current ASN: AS18558; Riverside County Office of Education
Routed prefix: 204.100.0.0/16; Most specific route covering this prefix
ASNs over time: 1; 1 announcement record
RIR allocation: ARIN; United States · 204.100.0.0/16

Routing data · Oct 24, 2026, 02:18 UTC

ASN historyEvery routed prefix covering 204.100.0.0/16

Prefix	ASN	Name	Registered country	First seen (UTC)	Last seen (UTC)	Status
204.100.0.0/16	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing

More specific routes135 total

Prefix	ASN	Name	Registered country	First seen (UTC)	Last seen (UTC)	Status
204.100.8.0/21	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.16.0/21	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.32.0/22	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.38.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.40.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.41.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.43.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.44.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.56.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.58.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.59.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.60.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.61.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.65.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.66.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.67.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.68.0/22	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.72.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.73.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.74.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.75.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.76.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.77.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.78.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.79.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.80.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.81.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.82.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.87.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.88.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.89.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.90.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.91.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.92.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.93.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.94.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.97.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.98.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.99.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.103.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.105.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.114.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.115.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.116.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.117.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.118.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.119.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.120.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.121.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.122.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.123.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.124.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.125.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.126.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.127.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.128.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.129.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.130.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.131.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.132.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.133.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.134.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.136.0/22	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.149.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.150.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.151.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.152.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.153.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.154.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.155.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.156.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.157.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.158.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.159.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.165.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.166.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.167.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.168.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.169.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.170.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.171.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.172.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.173.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.174.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.175.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.180.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.181.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.182.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.183.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.184.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.185.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.186.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.187.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.188.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.189.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.190.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.191.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.192.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.193.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.194.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.200.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.201.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.202.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.203.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.204.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.205.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.206.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.207.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.208.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.209.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.210.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.211.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.212.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.213.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.214.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.220.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.223.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.224.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.225.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.226.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.228.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.229.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.230.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.231.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.232.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.233.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.234.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.235.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.236.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.237.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.238.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.239.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.242.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.243.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-24 02:18	Announcing
204.100.106.0/24	AS18558	Riverside County Office of Education	United States	Before monitoring	2026-10-23 04:19	Stopped

Change logAll changes

The routes covering this address have had no origin changes since ASNBase started monitoring.

Look up another address

RIR allocation record

Registry: ARIN
Allocated block: 204.100.0.0/16
Country: United States
Allocation date: 1994-07-13
Status: allocated

From the RIRs’ delegated statistics files. Shows where the addresses are registered, not where they are used.

How monitoring works

Every 2 hours ASNBase takes the bgp.tools global routing table (prefix → origin ASN) and compares it with the previous one. The detected time is the time of that comparison; the actual change can be up to about 2 hours earlier.
Only routes seen by more than 100 bgp.tools peers are listed as changes; routes with less visibility are only kept in the history.
A new announcement counts only if it is still in the next routing table, and a withdrawal only if the prefix is missing from two tables in a row, so short flaps are ignored.
ASNBase has been monitoring since 2026-10-19. “Before monitoring” under “First seen” means the route was already announced when monitoring started; the earlier date is unknown.
Prefixes first seen during the first day of monitoring do not count as new announcements: most of them were simply missing from the table at the moment monitoring started.
Countries and regions follow the ASN’s registration, not the actual location of the IP addresses.