inet6num: 2001,4d38,,/32 netname: IT-ENTER-20050825 country: IT org: ORG-ES8-RIPE admin-c: RG1940-RIPE tech-c: RG1940-RIPE notify: firstname.lastname@example.org status: ALLOCATED-BY-RIR mnt-by: RIPE-NCC-HM-MNT mnt-by: MNT-ENTER mnt-lower: ENTER-NOC mnt-lower: MNT-ENTER mnt-routes: ENTER-NOC created: 2005-08-25T13,02,24Z last-modified: 2016-12-22T14,52,10Z source: RIPE organisation: ORG-ES8-RIPE org-name: ENTER S.r.l. org-type: LIR address: Via Stefanardo da Vimercate, 28 address: 20128 address: Milano address: ITALY phone: +39 02 25514300 fax-no: +39 02 25514303 abuse-c: AR15768-RIPE admin-c: MI1008-RIPE mnt-ref: ENTER-NOC mnt-ref: MNT-ENTER mnt-ref: RIPE-NCC-HM-MNT mnt-by: RIPE-NCC-HM-MNT mnt-by: MNT-ENTER created: 2004-04-17T11,30,53Z last-modified: 2016-12-22T14,52,40Z source: RIPE e-mail: email@example.com person: Raimondo Giarratana address: Enter S.r.l. address: via Stefanardo da Vimercate, 28 address: 20128 Milano (MI) address: IT phone: +39 2 25514300 fax-no: +39 2 25514303 nic-hdl: RG1940-RIPE e-mail: firstname.lastname@example.org created: 2004-04-14T08,48,42Z last-modified: 2016-04-06T12,00,49Z mnt-by: RIPE-NCC-LOCKED-MNT source: RIPE route6: 2001,4d38,,/32 descr: ENTER-IT-BLK origin: AS12850 remarks: All kind of abuse from this network remarks: should be reported to email@example.com mnt-by: ENTER-NOC created: 2008-06-05T12,16,40Z last-modified: 2008-06-05T12,16,40Z 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.