REVIEW OF ADDRESSINGEMM-E6 User’s Guide1-251.10.3 Identifying IP Address ClassesIn the event that you have an existing IP address and need to quicklydetermine what fields are available for Host IP address configuration,make that determination based on the binary value of the first DDN field.Tables 1-1 to 1-3 show that different address classes have different initialbits in the first octet. A Class A address, for example, will always have azero as the first bit of the first octet. To identify an IP address’ class,convert the decimal value of the first DDN field to binary.Example: 132.177.118.24Convert first DDN field to binary: 13210 = 100001002Since the first two bits of the octet are 102, the address is Class B. Refer tothe IP address Classes tables, each Class B address utilizes the first twofields for a Network ID (132.177.118.24), while the remaining two fields(132.177.118.24) are the Host ID.1.10.4 Subnet AddressesSubnet addresses are used to partition an IP network into multiplesubnetworks or subnets. The use of subnet addresses adds an additionallayer of hierarchy to the IP addressing scheme. This additional addressinglayer facilitates isolation, control, and administration of users within thenetwork, at a cost of reduction in total available Host IDs. This is done bygrouping hosts into separate subnets. To use the above Class B address,132.177.118.24, as an example, the last two fields are available for theassignment of Host IDs. If the Network Manager desired to use subnets,the third field, 118, could become common to a series or group of hostswith a common physical location or intended purpose.Example (Class B):132.177.118.24{{{Net ID Host IDSubnet Number Host Number{
