# Analyzing IP Networks – Answers, Exercise 2

Today’s post lists the answers to the previous post’s question, with a few comments, with a place to discuss. Nothing snazzy, but it does hit the fundamentals. Enjoy!

## Class, Network ID, and Network Broadcast

The Network ID can be derived from the class A, B, or C DDN value by copying the network octets, and writing a 0 for the rest of the octets. Similarly, the network broadcast address can be found by using the same logic, but writing a 255 instead of 0 for the host octets. Table 2 shows the class for each of the five problems, along with the derived network ID and network broadcast address for each class A, B, or C address.

 DDN Value Class Network ID Network Broadcast Address 1 9.9.9.9 A 9.0.0.0 9.255.255.255 2 99.99.99.99 A 99.0.0.0 99.255.255.255 3 199.199.199.199 C 199.199.199.0 199.199.199.255 4 119.119.119.119 A 119.0.0.0 119.255.255.255 5 229.229.229.229 D N/A N/A

To find the range of IP addresses that can be used by hosts in the (unsubnetted) classful network, just add 1 to the network ID and subtract 1 from the network broadcast address. Table 3 shows the results for these five problems.

#### Table 3: Ranges of Usable Addresses

 Network ID Lowest Usable Host Address Highest Usable Host Address Network Broadcast Address 1 9.0.0.0 9.0.0.1 9.255.255.254 9.255.255.255 2 99.0.0.0 99.0.0.1 99.255.255.254 99.255.255.255 3 199.199.199.0 199.199.199.1 199.199.199.254 199.199.199.255 4 119.0.0.0 119.0.0.1 119.255.255.254 119.255.255.255 5 N/A N/A N/A N/A
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1. Chris September 25, 12:10

Good thanks

2. Len October 17, 18:13

Better 2nd exercise!

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