AS11212 COUNTY-OF-SONOMA

COUNTY-OF-SONOMA is the network of Sonoma County, California — county government in the North Bay, seat at Santa Rosa. It is a small, multihomed public-sector network built entirely on provider-assigned address space.

What it's used for

County government IT: departmental systems, mail gateways and public-facing county services. Reverse DNS confirms the first-party use directly — 209.77.204.5 resolves to ipmail1.sonoma-county.org and a neighbouring address to a generic host under the same sonoma-county.org domain, the county's own web presence.

Notable

The three announced prefixes come from three different sources, and that is the detail worth understanding. 50.233.206.0/23 is registered under a Comcast network handle, 209.77.204.0/24 under SBCIS-101815-124837 (SBC Internet Services, now AT&T), and 12.202.169.0/24 under COUNTY-O43-169 inside AT&T's legacy 12.0.0.0/8. None of them is registered to the county as a direct allocation. Three registrants against one holder can be a leased-address warning sign in other contexts; here every one of them is a carrier reassignment to the customer, which is the ordinary way a county obtains routable space from each of its ISPs.

Interesting

The routing totals — 3 prefixes, 1,024 addresses, no IPv6, 2 observed BGP neighbours — are modest for a county serving roughly half a million residents. That is the norm for local government: most of the population never touches the county's routed space, so the address footprint reflects staff and services, not citizens.