Mistake #2

This is the problem that was randomly generated with my answers:

IP = 205 . 68 . 198 . 233 / 29


   Mask = 255 . 255 . 255 . 1 1 1 1 1 0 0 0
      Convert 233 to bin:   1 1 1 0 1 0 0 1
                            ----------------
      Do bit-wise AND:      1 1 1 0 1 0 0 1 (= 232)


      Magic = 8

Find the Answers for each

What is the Dotted Decimal Subnet Mask? 255 . 255 . 255 . 248

Find this SubNetwork 205 . 68 . 198 . 232

Find the First useable IP address 205 . 68 . 198 . 233

Find the Broadcast address 205 . 68 . 198 . 239

Find the Last useable IP address 205 . 68 . 198 . 238

What is the Total Number of IPs per Subnet? 32 - 29 = 3 ; 2³ = 8

How many useable Hosts Addresses per subnet? 8 - 2 = 6

What is the Next Subnetwork Number? 205 . 68 . 198 . 240

```
What IP Class is this? Class C
```

What is the 15th subnetwork number? 205 . 68 . 198 . 112

As you can see, I got number 10 wrong. The correct answer should have been:

10. 205 . 68 . 198 . 120

What did I do wrong?

I counted subnetwork number zero as the first subnetwork. Although some networks do use network number zero, for the puposes of subnetting, never count subnetwork zero! Start counting at the next one up. In this case, 205 . 68 . 198 . 8 would have been subnetwork number 1, making
205 . 68 . 198 . 120 subnetwork number 15, not 205 . 68 . 198 . 112.

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