Overlapping VLSM Subnets – Speed Test 2 Answers

The answer for Overlapping VLSM Subnets Speed Test 2 are below the fold! Here’s a complete list of related posts:

• • • Intro to overlapped subnet problems
    • All Overlapped Subnet problems
    • IPv4 Addressing Drills

Answer

No overlaps

While following the process helps, this one was pretty easy if you stepped back from the math and noticed that most of the IP addresses differed in the 2^nd octet. The masks were all at least 16 bits long, so none of the subnet ID and subnet broadcast calculations would change the first two octets. Just to repeat the process, in case you’re learning how, 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.