AS11517 BLUE-CROSS-AND-BLUE-SHIELD-OF-MINNESOTA

BLUE-CROSS-AND-BLUE-SHIELD-OF-MINNESOTA is the Minnesota licensee of the Blue

Cross Blue Shield Association, a nonprofit health insurer. The AS carries the

insurer's own corporate network, nothing else.

What it's used for

• Enterprise connectivity for a health plan: member and provider portals, claims systems, corporate offices, and the private interconnects that a US health insurer needs with providers and clearinghouses.
• RIS sees 17 announced IPv4 prefixes totalling 7,936 addresses, no IPv6, and only 2 observed BGP neighbours. Two neighbours against eight thousand addresses is the signature of a multihomed end site: the company buys transit from a pair of providers and sells nothing onward.

Notable

• Every prefix RIS sees is carved out of a single 159.136.0.0/16 — a stack of /22s, /23s, and /24s such as 159.136.24.0/22, 159.136.8.0/23, and 159.136.145.0/24. The deaggregation is internal segmentation of one legacy allocation, not an assembled inventory, and it is what a large enterprise looks like when it announces per-datacentre or per-function blocks separately.
• All sampled prefixes register to Blue Cross & Blue Shield of Minnesota under a single ARIN handle, USBCBSMN01. Registrant and holder agree everywhere, so there is no leased-space or third-party pattern to worry about.

Interesting

• Reverse DNS did not answer on the addresses sampled, which for a network like this is unremarkable and proves nothing either way. A health insurer's routed space is mostly internal and partner-facing rather than public web hosting, so there is little reason for most of it to carry public PTRs. The registration and the routing shape, not DNS, are what identify this network.