AS11971 Pfizer Inc.
2620:1fd:20::/44 - PFIZERNET
V6NetHandle: NET6-2620-1FD-1 OrgID: PFIZER Parent: NET6-2620-1 NetName: PFIZERNET NetRange: 2620:1FD:: - 2620:1FD:FFF:FFFF:FFFF:FFFF:FFFF:FFFF NetType: assignment OriginAS: 11971, 7068, 36393 RegDate: 2014-05-19 Updated: 2014-05-19 Source: ARIN OrgID: PFIZER OrgName: Pfizer Inc. CanAllocate: Street: 235 E. 42nd Street City: New York State/Prov: NY Country: US PostalCode: 10017-5755 RegDate: 1991-05-09 Updated: 2015-10-07 OrgAdminHandle: PAR31-ARIN OrgNOCHandle: PAR31-ARIN OrgTechHandle: PAR31-ARIN OrgAbuseHandle: PAR31-ARIN OrgAbuseHandle: NETAB18-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.