104.204.136.0/21

NetHandle:      NET-104-204-0-0-2
OrgID:          C05555795
Parent:         NET-104-204-0-0-1
NetName:        ACN-BB-CANADA-104-204
NetRange:       104.204.0.0 - 104.204.255.255
NetType:        reassignment
OriginAS:       19397
RegDate:        2015-01-06
Updated:        2015-01-06
Source:         ARIN


OrgID:          C05555795
OrgName:        ACN
CanAllocate:    
Street:         1100 Ave. des Canadiens de Montreal
City:           Montreal
State/Prov:     QC
Country:        CA
PostalCode:     H3B 2S2
RegDate:        2015-01-06
Updated:        2015-01-06
Source:         ARIN

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.