2600:6:ff81::/48 - SPRINT-MIAMI-POP
V6NetHandle: NET6-2600-6-FF81-1 OrgID: SMP-37 Parent: NET6-2600-2 NetName: SPRINT-MIAMI-POP NetRange: 2600:6:FF81:: - 2600:6:FF81:FFF:FFFF:FFFF:FFFF:FFFF NetType: reassignment RegDate: 2017-10-18 Updated: 2017-10-18 Source: ARIN OrgID: SMP-37 OrgName: Sprint Miami POP CanAllocate: Street: Sprint Miami POP City: Miami State/Prov: FL Country: US PostalCode: 33132 RegDate: 2013-12-05 Updated: 2013-12-05 OrgAbuseHandle: SIE-ARIN OrgAdminHandle: SIE-ARIN OrgTechHandle: SIE-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.