222.253.184.0/21

inetnum:        222.253.176.0 - 222.253.191.255
netname:        VNPTinfrastructure-NET
country:        vn
descr:          Vietnam Posts and Telecommunications(VNPT)
admin-c:        NXC1-AP
tech-c:         KNH1-AP
status:         ASSIGNED NON-PORTABLE
mnt-by:         MAINT-VN-VNPT
last-modified:  2008-10-16T02:55:19Z
source:         APNIC


person:         Khanh Nguyen Hien
nic-hdl:        KNH1-AP
e-mail:         huypt@vnpt.vn
address:        Vietnam Datacommunications Company (VDC)
address:        Lo IIA Lang Quoc te Thang Long, Cau Giay, Ha Noi
phone:          +84-4-3793 0563
fax-no:         +84-4-32811506
country:        VN
mnt-by:         VNPT
last-modified:  2016-09-08T05:04:38Z
source:         APNIC

person:         Nguyen Xuan Cuong
nic-hdl:        NXC1-AP
e-mail:         huypt@vnpt.vn
address:        Vietnam Posts and Telecommunications (VNPT)
address:        57 Huynh Thuc Khang
address:        Hanoi, Vietnam
phone:          +84-4-37741236
fax-no:         +84-4-37741205
country:        VN
mnt-by:         MAINT-VN-VNPT
last-modified:  2016-06-03T07:56:34Z
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.