AS16417 Cisco Systems Ironport Division
2620:101:2005::/48 - IRONP-V6-ARIN
V6NetHandle: NET6-2620-101-2000-1 OrgID: CISL-7 Parent: NET6-2620-1 NetName: IRONP-V6-ARIN NetRange: 2620:101:2000:: - 2620:101:201F:FFFF:FFFF:FFFF:FFFF:FFFF NetType: assignment OriginAS: 30238, 16417, 30215 RegDate: 2010-12-21 Updated: 2018-08-15 Source: ARIN OrgID: CISL-7 OrgName: Cisco Systems Ironport Division CanAllocate: Street: 170 West Tasman Drive City: San Jose State/Prov: CA Country: US PostalCode: 95134 RegDate: 2010-11-09 Updated: 2018-08-15 OrgTechHandle: WIECK1-ARIN OrgTechHandle: KLEEG-ARIN OrgTechHandle: ISO3-ARIN OrgTechHandle: BOUDJ-ARIN OrgNOCHandle: WIECK1-ARIN OrgNOCHandle: ISO3-ARIN OrgAdminHandle: ISO3-ARIN OrgAbuseHandle: INA15-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.