Chapter 5 began with a look at IP addressing basics. This included an overview of the binary-decimal conversion process. It continued with an introduction to classful IP addressing, where we outlined how the five classes of addresses are identified, and the number of hosts that each address range supports. The number of available Class A, B, and C networks were also calculated.
An overview of IP addressing rules outlined the eight key rules with respect to host addressing, such as the rule that mandates that the host portion of an address cannot be set to all binary 0s or all binary 1s. The concept and purpose of a subnet mask was introduced, including its relationship to IP addresses in defining the split between the network and host portion of an address. Default subnet mask values and when they are used were also examined.
A look at private IP addressing provided insight into the flexibility that using these addresses provides to organizations, as well as their purpose in helping to avoid the exhaustion of the current IPv4 address space. The special subnet masks associated with the three private ranges were also examined, along with the ranges of addresses that each supports.
An overview of subnetting provided insight into reasons for deciding to subnet a network. It continued by determining the subnet and host per subnet requirements that should be determined when characterizing a network. The process for determining custom subnet masks was covered in detail, including an overview of how bits are stolen from the host portion of the mask in order to allow subnets to be defined within the address space. Calculating the number of subnets and hosts per subnet available based on a given mask value was also looked at.
Next we looked at defining the ranges of addresses that were valid on a given subnet, including the process for determining the beginning and the end of a given range. This included an overview of ranges associated with Class A, B, and C addresses in custom subnetting situations. A subnetting challenge question was used to show how even questions that appear difficult are easy to solve if the rules outlined are followed.
The subnetting shortcut provided an overview of a quick and easy method of determining both custom subnet masks and their associated address ranges. It can be used as a simple reference for exam purposes.
The process of determining whether hosts are local or remote to one another was looked at next. We learned that the ANDing process provides a way to not only determine whether hosts are local or remote, but also to find the network ID associated with a given IP address.
A look at classless addressing provided insight into how addresses are now more commonly looked at in this manner rather than by class. An overview of CIDR provided insight to supernetting, address aggregation, and slash notation.