2a04:4300::/48 - UK-IMIMOBILE-20130621
inet6num: 2a04,4300,,/29 netname: UK-IMIMOBILE-20130621 country: GB org: ORG-IEL11-RIPE admin-c: SU791-RIPE tech-c: SU791-RIPE status: ALLOCATED-BY-RIR mnt-by: RIPE-NCC-HM-MNT mnt-by: imimobile mnt-routes: imimobile notify: firstname.lastname@example.org created: 2013-06-21T13,51,37Z last-modified: 2016-10-13T15,17,58Z source: RIPE organisation: ORG-IEL11-RIPE org-name: IMIMOBILE EUROPE LTD org-type: LIR address: Tempus Court, Bellfield Road address: HP13 5HA address: HIGH WYCOMBE address: UNITED KINGDOM phone: +441494750500 fax-no: +441494750800 e-mail: email@example.com mnt-ref: RIPE-NCC-HM-MNT mnt-ref: imimobile mnt-by: RIPE-NCC-HM-MNT mnt-by: imimobile abuse-c: AM33146-RIPE created: 2013-06-18T10,10,08Z last-modified: 2016-10-13T15,21,07Z source: RIPE role: Support UK address: 1 Cliveden Office Village address: Lancaster Road address: High Wycombe address: HP12 3YZ e-mail: firstname.lastname@example.org nic-hdl: SU791-RIPE mnt-by: imimobile created: 2013-06-19T14,16,59Z last-modified: 2013-06-19T14,16,59Z source: RIPE
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.