Overlapping VLSM Subnets – Speed Test 1 Answers

 In 200-301 V1 Appendices, CCENT-OLD

The answer for Overlapping VLSM Subnets Speed Test 1 are below the fold!

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Answer

 

Items 2 and 5 (from the original list) overlap

It helps to sort the subnet IDs as part of solving the problem. In fact, here’s the process I suggest when learning:

 1) Find the subnet IDs (if starting with IP address/prefix combinations)

2) List from lowest subnet ID to highest

3) List the broadcast address for each subnet next to the subnet ID

4) Compare adjacent entries to look for overlaps

5) If you find an overlap, when comparing the next item, compare to all subnets already known to overlap

Once sorted, you can find the first pair of overlaps working through the list sequentially. Here’s the sorted list.

 

Subnet ID Subnet Broadcast
10.25.46.0 10.25.47.255
10.25.48.0 10.25.55.255
10.25.64.0 10.25.79.255
10.25.88.128 10.25.88.255
10.25.96.0 10.25.99.255
10.25.99.96 10.25.99.99

Overlapping VLSM Subnets - Speed Test 1
Overlapping VLSM Subnets - Speed Test 2
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Bav

Not really a huge difference but I find sorting them 1st works better for me. I need to sort them anyway so may as well do this before I calculate the ranges.

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