TWiki> Main Web>ComputerNetworksandTelecommunications2012>SubnetPracticeExamples (2012-12-06, JimSkon) EditAttach

Network address: 192.168.10.0

Subnet mask: 255.255.255.224

1. How many subnets?

Answer... Hide Ans: 6

2. How many hosts?

Answer... Hide Ans: 30

3. What are the valid subnets?

Answer... Hide Ans: 32, 64, 96, 128, 160, 192

4. Fill in the table below.

Subnet 1 | Subnet 2 | Subnet 3 | Subnet 4 | Subnet 5 | Subnet 6 | Meaning |
---|---|---|---|---|---|---|

Answer... Hide 32 | Answer... Hide 64 | Answer... Hide 96 | Answer... Hide 128 | Answer... Hide 160 | Answer... Hide 192 | The subnet address |

Answer... Hide 33 | Answer... Hide 65 | Answer... Hide 97 | Answer... Hide 129 | Answer... Hide 161 | Answer... Hide 193 | The first valid host |

Answer... Hide 62 | Answer... Hide 94 | Answer... Hide 126 | Answer... Hide 158 | Answer... Hide 190 | Answer... Hide 222 | Our last valid host |

Answer... Hide 63 | Answer... Hide 95 | Answer... Hide 127 | Answer... Hide 159 | Answer... Hide 191 | Answer... Hide 223 | The broadcast address |

Network address: 192.168.10.0 Subnet mask: 255.255.255.240 1. How many subnets?

Answer... Hide Ans: 14

2. How many hosts?

Answer... Hide Ans: 14

3. What are the valid subnets?

Answer... Hide Ans: 16, 32, 48, 64, 80, 96, 112, 128, 144, 160, 176, 192, 208, 224

4. Fill in the table below.

Subnet | 16 | 32 | 48 | 64 | 80 | 96 | 112 | 128 | 144 | 160 | 176 | 192 | 208 | 224 |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|

First Host | . | . | . | . | . | . | . | . | . | . | . | . | . | . |

Last Host | ||||||||||||||

Broadcast |

Subnet | 16 | 32 | 48 | 64 | 80 | 96 | 112 | 128 | 144 | 160 | 176 | 192 | 208 | 224 |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|

First Host | 17 | 33 | 49 | 65 | 81 | 97 | 113 | 129 | 145 | 161 | 177 | 193 | 209 | 225 |

Last Host | 30 | 46 | 62 | 78 | 94 | 110 | 126 | 142 | 158 | 174 | 190 | 206 | 222 | 238 |

Broadcast | 31 | 47 | 63 | 79 | 95 | 111 | 127 | 143 | 159 | 175 | 191 | 207 | 223 | 239 |

Network address: 192.168.10.0 Subnet mask: 255.255.255.248 1. How many subnets?

Answer... Hide Ans: 30

2. How many hosts?

Answer... Hide Ans: 6

3. What are the valid subnets?

Answer... Hide Ans: 8, 16, 24, 32, 40, 48, 56, 64, 72, 80, 88, 96, 104, 112, 120, 128, 136, 144, 152, 160, 168, 176, 184, 192, 200, 208, 216, 224, 232, 240

4. Fill in the table below (only the first three and last three subnets).

Subnet | 8 | 16 | 24 | 224 | 232 | 240 |
---|---|---|---|---|---|---|

First Host | ||||||

Last Host | ||||||

Broadcast |

Subnet | 8 | 16 | 24 | 224 | 232 | 240 |
---|---|---|---|---|---|---|

First Host | 9 | 17 | 25 | 225 | 233 | 241 |

Last Host | 14 | 22 | 30 | 230 | 238 | 246 |

Broadcast | 15 | 23 | 31 | 231 | 239 | 247 |

Network address: 192.168.10.0 Subnet mask: 255.255.255.252 1. How many subnets?

Answer... Hide Ans: 62

2. How many hosts?

Answer... Hide Ans: 2

3. What are the valid subnets?

Answer... Hide Ans: 4, 8, 12 etc., all the way to 248

4. Fill in the table below (only the first three and last three subnets).

Subnet | 4 | 8 | 12 | 240 | 244 | 248 |
---|---|---|---|---|---|---|

First Host | ||||||

Last Host | ||||||

Broadcast |

Subnet | 4 | 8 | 12 | 240 | 244 | 248 |
---|---|---|---|---|---|---|

First Host | 5 | 9 | 13 | 241 | 245 | 249 |

Last Host | 6 | 10 | 14 | 242 | 246 | 250 |

Broadcast | 7 | 11 | 15 | 243 | 247 | 251 |

Write the subnet, broadcast address and valid host range for the following:

1. 172.16.10.5 255.255.255.128

Answer... Hide Ans: Subnet is 172.16.10.0, broadcast is 172.16.10.127 and valid host range is 172.16.10.1 to 126. You need to ask yourself, “Is the subnet bit in the fourth octet on or off?” If the host address has a value of less than 128 in the fourth octet, then the subnet bit must be off. If the value of the fourth octet is higher than 128, then the subnet bit must be on. In this case, the host address is 10.5 and the bit in the fourth octet must be off. The subnet must be 172.16.10.0.

2. 172.16.10.33 255.255.255.224

Answer... Hide Ans: Subnet is 172.16.10.32, broadcast is 172.16.10.63 and valid host range is 172.16.10.33 to 10.62. 256-224=32. 32+32=64. The subnet is 10.32 and the next subnet is 10.64, so the broadcast address must be 10.63.

3. 172.16.10.65 255.255.255.192

Answer... Hide Ans: Subnet is 172.16.10.64, broadcast is 172.16.10.127 and valid host range is 172.16.10.65 to 172.16.10.126. 256-192=64. 64+64=128, so the network address must be 172.16.10.64, with a broadcast of 172.16.10.127.

4. 172.16.10.17 255.255.255.252

Answer... Hide Ans: Network is 172.16.10.16, broadcast is 172.16.10.19 and valid host range is 172.16.10.17 to 18. 256-252=4. 4+4=8, plus 4=12, plus 4=16, plus 4=20. So the subnet is 172.16.10.16 and the broadcast must be 10.19.

5. 172.16.10.33 255.255.255.240

Answer... Hide Ans: Network is 172.16.10.32, broadcast is 172.16.10.47 and valid host range is 172.16.10.33 to 46. 256-240=16. 16+16=32, plus 16=48. The subnet is 172.16.10.32 and the broadcast is 172.1610.47.

6. 192.168.100.25 255.255.255.252

Answer... Hide Ans: Subnet is 192.168.100.24, broadcast is 192.168.100.27 and valid host range is 192.168.100.25 to 26. 256-252=4. 4+4=8, plus 4=12, plus 4=16, plus 4=20, plus 4=24, plus 4=28. The subnet is 100.24 and the broadcast is 100.27.

7. 192.168.100.17, with 4 bits of subnetting

Answer... Hide Ans: Subnet is 192.168.100.16, broadcast is 192.168.100.31 and valid host range is 192.168.100.17 to 30. 256-240=16. 16+16=32. The subnet is, then, 100.16 and the broadcast is 100.31 because 32 is the next subnet.

8. 192.168.100.66, with 3 bits of subnetting

Answer... Hide Ans: Subnet is 192.168.100.64, broadcast is 192.168.100.95 and valid host range is 192.168.100.65 to 94. 256-224=32. 32+32=64, plus 32=96. The subnet is 100.64 and the broadcast is 100.95.

9. 192.168.100.17 255.255.255.248

Answer... Hide Ans: Subnet is 192.168.100.16, broadcast is 192.168.100.23 and valid host range is 192.168.100.17 to 22. 256-248=8. 8+8=16, plus 8=24. The subnet is 16 and the broadcast is 23.

10. 10.10.10.5 255.255.255.252

Answer... Hide Ans: Subnet is 10.10.10.4, broadcast is 10.10.10.7 and valid host range is 10.10.10.5 to 6. 256-252=4. 4+4=8.

-- JimSkon - 2012-11-07

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Topic revision: r2 - 2012-12-06 - JimSkon

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