2001:1890:e100::/48 - ATT-CERF
V6NetHandle: NET6-2001-1890-E100-1 OrgID: CERF Parent: NET6-2001-1890-1 NetName: ATT-CERF NetRange: 2001:1890:E100:: - 2001:1890:E1FF:FFFF:FFFF:FFFF:FFFF:FFFF NetType: reallocation RegDate: 2012-05-30 Updated: 2012-05-30 Source: ARIN OrgID: CERF OrgName: CERFnet CanAllocate: Street: 5738 Pacific Center Blvd City: San Diego State/Prov: CA Country: US PostalCode: 92121 Comment: Contact AT&T Abuse (email@example.com) for policy abuse issues. Comment: All policy abuse issues sent to other POCs will be disregarded. RegDate: 1989-04-18 Updated: 2017-01-28 OrgAbuseHandle: ATTAB-ARIN OrgAdminHandle: NETWO10-ARIN OrgTechHandle: NETWO10-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.