Q.1 Suppose you have a class c network with a subnet mask 255.255.255.240. if you want to subnet your network 192.168.2.0 then find the number of subnets, number of host per subnetwork and find full and usable host range of first four networks?
Explanation:-
Subnet mask 255.255.255.240
Convert in binary 11111111.11111111.11111111.11110000
it means IP address have 28 Network bit but in subnetting we work only 4 bit of last octet .
Find No of Subnet
So No of Subnet will be 2 4 =16 it means 16 subnet will be possible
Subnets values lying between 0000 to 1111
Subnet value will be. 0000, 0001,0010,0011,0100,0110,0111,1000,1001,1010,1011,1100,1101,1110, 1111
Find No of Host
So No of Host will be 2 4 =16 it means 16 Host will be possible in each subnet
No of Usable host 16-2=14 usable host are available for each subnet. two host bits are reserve bits first bit is used for subnet id and last bit is used for broadcast id.
Also Read:-Stop and Wait ARQ MCQs
Find Network and Broadcast address
We want to subnet the network 192.168.2.0 with Subnet mask 255.255.255.240
Convert 192.168.2.0 and Subnet mask 255.255.255.240 in binary
255.255.255.240= 11111111.11111111.11111111.11110000
192.168.2.0 = 11000000.10101000.00000010.00000000
First method
Find the Network Address: Perform AND Operation between IP Address and Subnet Mask
Do the AND operation of IP Address and subnet mask.
AND operation:
After AND operation result is 11000000.10101000.00000010.00000000
it means 192.168.2.0 is network id
Find the Broadcast Address: Perform OR Operation between IP Address and Inverted Subnet Mask
if you want to find the broadcast address, invert the bits of subnet mask change 0s to 1s and 1s to 0s. Perform OR Operation between IP Address and Inverted Subnet Mask
255.255.255.240= 11111111.11111111.11111111.11110000
invert all the bit of subnet mask
00000000.0000000.00000000.00001111
192.168.2.0 = 11000000.10101000.00000010.00000000
Then we perform OR Operation Between Them
Broad cast address 192.168.2.15
Also Read:-Stop and Wait ARQ MCQs
Second method
255.255.255.240= 11111111.11111111.11111111.11110000
192.168.2.0 = 11000000.10101000.00000010.00000000
reserve four bit like subnet mask and rest other bit replace with zero
Then Network address is 11000000.10101000.00000010.00000000
it means 192.168.2.0 is network address
if we want to find broad cast address reserve four bit like subnet mask and rest other bit replace with one
Then Broadcast address is 11000000.10101000.00000010.00001111
Broad cast address 192.168.2.15
Find Range
according to question we find range of four subnet although 16 subnets will we possible
1st 11000000.10101000.00000010.00000000 to 11000000.10101000.00000010.00001111
it means 192.168.2.0 to 192.168.2.15
2nd 1000000.10101000.00000010.00010000 to 11000000.10101000.00000010.00011111
it means 192.168.2.16 to 192.168.2.31
3rd 11000000.10101000.00000010.00100000 to 11000000.10101000.00000010.00101111
it means 192.168.2.32 to 192.168.2.47
4th 11000000.10101000.00000010.00110000 to 11000000.10101000.00000010.00111111
it means 192.168.2.48 to 192.168.2.63
| Subnet Name | Network Address | Usable Host Range | Broadcast Address |
| 1st | 192.168.2.0 | 192.168.2.1-192.168.2.14 | 192.168.2.15 |
| 2nd | 192.168.2.16 | 192.168.2.17-192.168.2.30 | 192.168.2.31 |
| 3rd | 192.168.2.32 | 192.168.2.33-192.168.2.46 | 192.168.2.47 |
| 4th | 192.168.2.48 | 192.168.2.49-192.168.2.62 | 192.168.2.63 |
