CALCULATING A SUBNET MASK EXERCISE 2-1

EXERCISE 2-1: CALCULATING A SUBNET MASK 1. Your instructor has supplied you with a network address to use on your workgroup network. Write down the address you have been assigned. 10.2.1.15 255.255.0.0 To which IP address class does your network address belong? (Consult Table 2-1 in your textbook if you are not sure.) Class A What is the size of the network identifier in the address you've been assigned in bits? 16 bits 2. Subtract the number of network identifier bits from the number following the slash in the address your instructor has provided. 16 – 8 = 8 What does this value represent? Subnet bits 3. Calculate the value of 2˟ – 2, where x is the value you calculated in Step 2. 2 8 – 2 = 254 What does this value represent? Number of subnets 4. Subtract the number following the slash in the address your instructor has provided from 32. 32 – 16 = 16 What does this value represent? Host bits 5. Calculate the value of 2˟ - 2, where, x is the value you calculated in Step 4. 2 16 – 2 = 65534 What does this value represent? Number of hosts 6. Write a number of ones corresponding to the value after the slash in the address supplied by your instructor. For example, if the supplied address was 172.23.47.0/24, you would write 24 ones, as follows: 111111111111111111111111 1111111111111111 7. Add zeros after the ones to reach a total of 32 bits, and record the resulting value in the space below as in the following example: 11111111111111111111111100000000 11111111111111110000000000000000

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Transcript of CALCULATING A SUBNET MASK EXERCISE 2-1

Page 1: CALCULATING A SUBNET MASK EXERCISE 2-1

EXERCISE 2-1: CALCULATING A SUBNET MASK

1. Your instructor has supplied you with a network address to use on your workgroup network. Write down the address you have been assigned. 10.2.1.15 255.255.0.0 To which IP address class does your network address belong? (Consult Table 2-1 in your textbook if you are not sure.) Class A What is the size of the network identifier in the address you've been assigned in bits? 16 bits

2. Subtract the number of network identifier bits from the number following the slash in the address your instructor has provided. 16 – 8 = 8 What does this value represent? Subnet bits

3. Calculate the value of 2˟ – 2, where x is the value you calculated in Step 2. 28 – 2 = 254 What does this value represent? Number of subnets

4. Subtract the number following the slash in the address your instructor has provided from 32. 32 – 16 = 16 What does this value represent? Host bits

5. Calculate the value of 2˟ - 2, where, x is the value you calculated in Step 4. 216 – 2 = 65534 What does this value represent? Number of hosts

6. Write a number of ones corresponding to the value after the slash in the address supplied by your instructor. For example, if the supplied address was 172.23.47.0/24, you would write 24 ones, as follows: 111111111111111111111111 1111111111111111

7. Add zeros after the ones to reach a total of 32 bits, and record the resulting value in the space below as in the following example: 11111111111111111111111100000000 11111111111111110000000000000000

Page 2: CALCULATING A SUBNET MASK EXERCISE 2-1

8. Split the 32-bit value into four groups of eight bits each, and convert each group of eight to decimal form as in the following example. (See "Converting Binaries and Decimals" in Chapter 2 of your textbook if you need help performing the conversions.) 11111111 11111111 11111111 00000000 255 255 255 0 11111111 11111111 00000000 00000000 255 255 0 0

9. Write the four 8-bit decimal numbers using dotted decimal notation. 255.255.0.0 This value is the subnet mask that you will use for your workgroup network. Record the subnet mask in the Subnet Mask cell in Table 2-1 at the end of Exercise 2-2.