AS135905 VIETNAM POSTS AND TELECOMMUNICATIONS GROUP
2400:6540::/48 - VINAHOST-VN
inet6num: 2400:6540::/48 netname: VINAHOST-VN descr: VINAHOST COMPANY LIMITED descr: 351/31 No Trang Long, 13 Ward, Binh Thanh District, Ho Chi Minh City country: VN admin-c: NTTN1-AP tech-c: PVL4-AP status: ALLOCATED NON-PORTABLE mnt-by: MAINT-VN-VNNIC mnt-irt: IRT-VNNIC-AP last-modified: 2018-03-26T09:37:17Z 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.