2605:2800:1200::/48 - UTS-OTS-IPV6-32-2010
V6NetHandle: NET6-2605-2800-1 OrgID: UTS-2 Parent: NET6-2600-1 NetName: UTS-OTS-IPV6-32-2010 NetRange: 2605:2800:: - 2605:2800:FFFF:FFFF:FFFF:FFFF:FFFF:FFFF NetType: allocation RegDate: 2010-04-27 Updated: 2012-03-02 Source: ARIN OrgID: UTS-2 OrgName: University of Texas System CanAllocate: Street: Office of Telecommunication Services Street: P.O. Box 7580 City: Austin State/Prov: TX Country: US PostalCode: 78713-7580 RegDate: 1990-12-05 Updated: 2017-02-02 OrgAdminHandle: NAC25-ARIN OrgAbuseHandle: ABUSE3227-ARIN OrgTechHandle: ZU82-ARIN Source: ARIN
IP address ranges, or netblocks, are groups of related IP addresses. They are usually represented as a base IP address, followed by a slash, and then a netmask which represents how many IP addresses are contained within the netblock. This format is known as CIDR. You'll also sometimes see netblocks given as a start ip address, and an end ip address, or an ip address range.
Traffic works its way around the internet based on the routing table, which contains a list of networks and their associated netblocks.