Special Subnet Considerations
RFC 950 originally indicated that 0s and 1s should not be used in either host or subnet assignments.
- Special meaning in that 0.0.0.1 means host 1 on this subnet
Increasing pressure forced the use of all available bits for subnetting.
CIDR has no concept of subnets, therefore it has no concept of 0s or 1s being reserved.
You should be careful using all 0s or 1s in a subnet. A 1s subnet could be misinterpreted as an all-subnets broadcast.
- All 1s in the subnet field could direct a router to forward the packet to all subnets under the indicated network ID.