An extended network address includes both a network address and additional bits that represent the subnet number. Together, these two data elements support a two-level addressing scheme recognized ...

My book I'am reading IP fundamentals has gotten a bit confusing when getting combining several subnets which uses more bits for it's subnet number into one single subnet such as combining four /24 ...

The developers of the NANP did not anticipate every human being having a personal cell phone number, work cell phone number, office DID number, home phone number, and home fax line.