The document discusses subnetting Class C and Class B IP addresses using various subnet masks. It provides examples of subnetting the IP addresses 192.168.10.0, 172.16.0.0, 172.21.0.0, and 10.0.0.0 using subnet masks such as /25, /26, /17, and /19. For each example, it calculates the number of subnets and hosts, identifies the subnet ID and broadcast address ranges.

1. 4.0 PLANNING ADDRESSING STRUCTURE
4.1 IP ADDRESSING IN THE LAN
4.1.1 Custom Subnet Masks

2. Subnetting Class C Addresses
BINARY DECIMAL CIDR
0000 0000 0 /24
1000 0000 128 /25
1100 0000 192 /26
1110 0000 224 /27
1111 0000 240 /28
1111 1000 248 /29
1111 1100 252 /30

3. Example #1
192.168.10.0 /25
Default subnet masks:
255 . 255 . 255 . 0
1111 1111. 1111 1111. 1111 1111. 0000 0000
i. Custom subnet masks: /25
1111 1111. 1111 1111. 1111 1111. 1000 0000
255 . 255 . 255 . 128

4. ii. Number of valid hosts
27-2 = 126 hosts
iii. Number of subnets :
21 = 2 subnets
iv. Range:
256-128 = 128

5. SUBNET N.I.D B.I.D IP RANGE
0 192.168.10.0 192.168.10.127 192.168.10.1 - 192.168.10.126
1 192.168.10.128 192.168.10.255 192.168.10.129 - 192.168.10.254

6. Example #2
192.168.10.0 /26
Default subnet masks:
255 . 255 . 255 . 0
1111 1111. 1111 1111. 1111 1111. 0000 0000
i. Custom subnet masks: /26
1111 1111. 1111 1111. 1111 1111. 1100 0000
255 . 255 . 255 . 192

7. ii. Number of valid hosts
26-2 = 62 hosts
iii. Number of subnets :
22 = 4 subnets
iv. Range:
256-192 = 64

8. SUBNET N.I.D B.I.D IP RANGE
0 192.168.10.0 192.168.10.63 192.168.10.1 - 192.168.10.62
1 192.168.10.64 192.168.10.127 192.168.10.65 - 192.168.10.126
2 192.168.10.128 192.168.10.191 192.168.10.129 - 192.168.10.190
3 192.168.10.192 192.168.10.255 192.168.10.193 - 192.168.10.254

9. Subnetting Class B Addresses
SUBNET MASKS SUBNET MASKS
255.255.0.0 (/16) 255.255.255.0 (/24)
255.255.128.0 (/17) 255.255.255.128 (/25)
255.255.192. 0 (/18) 255.255.255.192 (/26)
255.255.224. 0 (/19) 255.255.255.224 (/27)
255.255.240. 0 (/20) 255.255.255.240 (/28)
255.255.248. 0 (/21) 255.255.255.248 (/29)
255.255.252. 0 (/22) 255.255.255.252 (/30)
255.255.254. 0 (/23)

10. Example #1
172.16.0.0 /17
Default subnet masks:
255 . 255 . 0 . 0
1111 1111. 1111 1111. 0000 0000. 0000 0000
i. Custom subnet masks: /17
1111 1111. 1111 1111. 1000 0000. 0000 0000
255 . 255 . 128 . 0

11. ii. Number of valid hosts
215-2 = 32, 766 hosts
iii. Number of subnets :
21 = 2 subnets
iv. Range:
256-128 = 128

12. SUBNET N.I.D B.I.D IP RANGE
0 172.16.0.0 172.16.127.255 172.16.0.1 – 172.16.127.254
1 172.16.128.0 172.16.255.255 172.16.128.1 – 172.16.255.254

13. Example #2
172.16.0.0 /18
Default subnet masks:
255 . 255 . 0 . 0
1111 1111. 1111 1111. 0000 0000. 0000 0000
i. Custom subnet masks: /18
1111 1111. 1111 1111. 1100 0000. 0000 0000
255 . 255 . 192 . 0

14. ii. Number of valid hosts
214-2 = 16, 382 hosts
iii. Number of subnets :
22 = 4 subnets
iv. Range:
256-192 = 64

15. SUBNET N.I.D B.I.D IP RANGE
0 172.16.0.0 172.16.63.255 172.16.0.1 - 172.16.63.254
1 172.16.64.0 172.16.127.255 172.16.64.1 - 172.16.127.254
2 172.16.128.0 172.16.191.255 172.16.128.1 - 172.16.191.254
3 172.16.192.0 172.16.255.255 172.16.192.1 - 172.16.255.254

16. Example #3
172.21.0.0 /25
Default subnet masks:
255 . 255 . 0 . 0
1111 1111. 1111 1111. 0000 0000. 0000 0000
i. Custom subnet masks: /25
1111 1111. 1111 1111. 1111 1111. 1000 0000
255 . 255 . 255 . 128

17. ii. Number of valid hosts
27-2 = 126 hosts
iii. Number of subnets :
29 = 512 subnets
iv. Range:
256-128 = 128

18. SUBNET N.I.D B.I.D IP RANGE
0 172.21.0.0 172.21.0.127 172.21.0.1 - 172.21.0.126
1 172.21.0.128 172.21.0.255 172.21.0.129 - 172.21.0.254
2 172.21.1.0 172.21.1.127 172.21.1.1 - 172.21.1.126
3 172.21.1.128 172.21.1.255 172.21.1.129 - 172.21.1.254
4 172.21.2.0 172.21.2.127 172.21.2.1 - 172.21.2.126
5 172.21.2.128 172.21.2.255 172.21.2.129 - 172.21.2.254
6 172.21.3.0 172.21.3.127 172.21.3.1 - 172.21.3.126
7 172.21.3.128 172.21.3.255 172.21.3.129 - 172.21.3.254
8 172.21.4.0 172.21.4.127 172.21.4.1 - 172.21.4.126
: : : :
: : : :
511 172.21.255.128 172.21.255.255 172.21.255.129 - 172.21.255.254

19. Example #5
172.21.0.0 /26
Default subnet masks:
255 . 255 . 0 . 0
1111 1111. 1111 1111. 0000 0000. 0000 0000
i. Custom subnet masks: /25
1111 1111. 1111 1111. 1111 1111. 1100 0000
255 . 255 . 255 . 192

20. ii. Number of valid hosts
26-2 = 62 hosts
iii. Number of subnets :
210 = 1024 subnets
iv. Range:
256-192 = 64

21. SUBNET N.I.D B.I.D IP RANGE
0 172.21.0.0 172.21.0.63 172.21.0.1 – 172.21.0.62
1 172.21.0.64 172.21.0.127 172.21.0.65 – 172.21.0.126
2 172.21.0.128 172.21.0.191 172.21.0.129 – 172.21.0.190
3 172.21.0.192 172.21.0.255 172.21.0.193 – 172.21.0.254
4 172.21.1.0 172.21.1.63
5 172.21.1.64 172.21.1.127
6 172.21.1.128 172.21.1.191
7 172.21.1.192 172.21.1.255
8 172.21.2.0 172.21.2.63
: : : :
: : : :
1023 172.21.255.192 172.21.255.255 172.21.255.193 – 172.21.255.254

22. Example #6
10.0.0.0 /10
Default subnet masks:
255 . 0 . 0 . 0
1111 1111. 0000 0000. 0000 0000. 0000 0000
i. Custom subnet masks: /10
1111 1111. 1100 0000. 0000 0000. 0000 0000
255 . 192 . 0 . 0

23. ii. Number of valid hosts
222-2 = 4, 194302 hosts
iii. Number of subnets :
22 = 4 subnets
iv. Range:
256-192 = 64

24. SUBNET N/W ADD B/CAST ADD HOST RANGE
0 10.0.0.0 10.63.255.255 10.0.0.1 - 10.63.255.254
1 10.64.0.0 10.127.255.255 10.64.0.1 – 10.127.255.254
2 10.128.0.0 10.191.255.255 10.128.0.1 – 10.191.255.254
3 10.192.0.0 10.255.255.255 10.192.0.1 – 10.255.255.254

25. Example #7
10.0.0.0 /19
Default subnet masks:
255 . 0 . 0 . 0
1111 1111. 0000 0000. 0000 0000. 0000 0000
i. Custom subnet masks: /19
1111 1111. 1111 1111. 1110 0000. 0000 0000
255 . 255 . 224 . 0

26. ii. Number of valid hosts
213-2 = 8190 hosts
iii. Number of subnets :
211 = 2048 subnets
iv. Range:
256-224 = 32

27. SUBNET N/W ADD B/CAST ADD HOST RANGE
0 10.0.0.0 10.0.31.255 10.0.0.1 – 10.0.31.254
1 10.0.32.0 10.0.63.255 10.0.32.1 – 10.0.63.254
2 10.0.64.0 10.0.95.255 10.0.64.1 – 10.0.95.254
3 10.0.96.0 10.0.127.255 10.0.96.1 – 10.0.127.254
4 10.0.128.0 10.0.159.255 10.0.128.1 – 10.0.159.254
5 10.0.160.0 10.0.191.255 10.0.160.1 – 10.0.191.254
6 10.0.192.0 10.0.223.255 10.0.192.1 – 10.0.223.254
7 10.0.224.0 10.0.255.255 10.0.224.1 – 10.0.255.254
8 10.1.0.0 10.1.31.255 10.1.0.1 -10.1.31.254
9 10.1.32.0 10.1.63.255 10.1.32.1 – 10.1.63.254
: : : :
2047 10.255.224.0 10.255.255.255 10.255.224.1 – 10.255.255.254