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2001:500:1::/48 - H-ROOT
V6NetHandle: NET6-2001-500-1-1 OrgID: UARL-1 Parent: NET6-2001-400-0 NetName: H-ROOT NetRange: 2001:500:1:: - 2001:500:1:FFFF:FFFF:FFFF:FFFF:FFFF NetType: allocation OriginAS: 1508, 13 RegDate: 2002-11-22 Updated: 2016-10-27 TechHandle: LAB2-ARIN Source: ARIN OrgID: UARL-1 OrgName: U.S. Army Research Laboratory CanAllocate: Street: 2800 Powder Mill Road City: Adelphi State/Prov: MD Country: US PostalCode: 20783 Comment: http://www.arl.army.mil RegDate: 1970-01-01 Updated: 2017-01-28 OrgTechHandle: HMK1-ARIN OrgAdminHandle: TGK8-ARIN OrgAbuseHandle: HMK1-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.