2001:df6:1800::/48 - IPv6-IDNIC-AXARVA-ID
inet6num: 2001:df6:1800::/48 netname: IPv6-IDNIC-AXARVA-ID descr: PT Axarva Media Teknologi descr: Corporate / Direct Member IDNIC descr: Gedung Raudha lt.1 A3-A5, descr: Jl. Terusan H.R Rasuna Said No.21, descr: Jakarta Selatan 12710 admin-c: AA821-AP tech-c: AA821-AP remarks: Send Spam & Abuse Reports to firstname.lastname@example.org country: ID mnt-by: MNT-APJII-ID mnt-irt: IRT-AXARVA-ID mnt-routes: MAINT-ID-AXARVA status: ASSIGNED PORTABLE last-modified: 2016-10-03T03:59:16Z source: APNIC
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.