AS1221 Telstra Pty Ltd
2001:8000::/20 - TELSTRAINTERNET41-AU-20041202
inet6num: 2001:8000::/20 netname: TELSTRAINTERNET41-AU-20041202 descr: Telstra Internet descr: Locked Bag 5744 descr: Canberra descr: ACT 2601 country: AU org: ORG-TC6-AP admin-c: TIAR-AP tech-c: TIAR-AP remarks: ----- remarks: Telstra Networks IPv6 assignment. remarks: All reports regarding SPAM or security breaches remarks: should be addressed to firstname.lastname@example.org remarks: ------ mnt-by: APNIC-HM mnt-lower: MAINT-AU-TIAR-AP status: ALLOCATED PORTABLE mnt-irt: IRT-TELSTRA-AU last-modified: 2017-09-26T23:28:55Z 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.