AS131283 HDFC Bank House
2405:a100:20::/44 - HDFCBANK-IN
inet6num: 2405:a100::/32 netname: HDFCBANK-IN descr: HDFC Bank House descr: Senapati Bapat Marg, descr: Lower Parel country: IN org: ORG-HBL3-AP admin-c: AD309-AP tech-c: AD309-AP mnt-routes: MAINT-HDFCBANK-IN mnt-irt: IRT-HDFCBANK-IN mnt-lower: MAINT-HDFCBANK-IN mnt-by: APNIC-HM status: ALLOCATED PORTABLE last-modified: 2017-10-04T13:07:05Z 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.