VLSM Design Drill #1
VLSM causes many #CCENT and #CCNA candidates much heartache. Today’s post shows a VLSM design exercise that is useful for exam prep as well as real life. The idea: begin with an existing design that happens to use VLSM. Then plan the next subnet to add to the network. Can you find a subnet number to use that doesn’t overlap with the existing subnets? Today’s post lists the question; next time, the answer. Details below the fold.
The Scenario
Your boss wants you to add a subnet to an existing design. The existing design already has these five subnets:
- 192.168.1.32/29
- 192.168.1.0/28
- 192.168.1.128/29
- 192.168.1.96/30
- 192.168.1.192/27
The boss cannot decide among three competing subnet masks. However, while he’s thinking about which mask to use, he wants you to practice VLSM and choose the subnet ID he would use for each of those three possible masks. He tells you that the new subnet ID must be part of class C network 192.168.1.0, that the new subnet must not overlap with the original five subnets, and that the new subnet ID must be the numerically lowest possible subnet ID (without breaking the other rules).
The following list details the prefix masks your boss is considering using for the new subnet. Choose the subnet ID you would recommend in each case.
1) /26
2) /27
3) /28
(Added by Wendell – spoiler alert! I pushed the actual post lower to avoid showing others that are still working.)
192.168.1.100/26
192.168.1.224/27
192.168.1.15/28
(Added by Wendell – again, adding space to avoid spoiling for others… more below)
1. None
2. 192.168.1.160/27
3. 192.168.1.16/28
1. None
2. 192.168.1.64/27
3. 192.168.1.16/28
[…] for some VLSM work for #CCENT and #CCNA today! Today’s post begins the analysis for the VLSM design drill posted earlier. The original post posed a scenario, with an existing subnet design that uses VLSM. Your job: plan […]
[…] #CCENT and #CCNA today! Today’s post is simple enough: this post wraps up the answer to the VLSM design drill posted earlier. Dive right in! Here’s the list of earlier posts in this […]
192.168.1.64/26
192.168.1.160/27
192.168.1.16/28