Subnet Blocks: Choose an Unused Address

5 questions0m 0s

Learn the skill

Within the same first three IPv4 numbers, /24 has 256 addresses, /25 has 128 and /26 has 64. A /26 block starts at last number 0, 64, 128 or 192. In these ordinary networks, the first address names the network and the last is broadcast. Do not assign either to a host or reuse an occupied address. Special /31 and /32 cases are outside this exercise.

Worked example

Separate example: 192.0.2.0/25 covers last numbers 0-127. Hosts are 1-126, giving 126 host addresses before counting any already in use.

One /24 row spans last numbers 0-255, two /25 blocks span 0-127 and 128-255, and four /26 blocks span 0-63, 64-127, 128-191 and 192-255. All begin with 192.0.2. — Each row divides the same address range. Locate the worksheet's block before choosing a host.

Workshop C / fictional address inventory

All addresses begin with 192.0.2. Workshop C uses /26 and must contain a new laptop ending in 150. Currently the gateway uses 129, a printer uses 140, and a server uses 160. These are the only three occupied addresses; the new laptop has not been assigned yet. Use only this paper inventory. Do not configure or contact real devices. For numeric questions, enter just the last number.

Question 1 What last number names Workshop C's network? Answer

Question 2 What is the last number of this block's broadcast address? Answer

Question 3 What is the greatest allowed ordinary host last number in this block? Answer

Question 4 How many host addresses remain unused before assigning the new laptop? Answer

Question 5 Which candidate could be another unused ordinary host in this block? 192.0.2.128 192.0.2.140 192.0.2.147