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An ISP is granted a block of addresses starting with 150.80.0.0/16. The ISP wants to distribute these blocks to 2600 customers as follows.
a. The first group has 200 medium-size businesses; each needs 128 addresses.
b. The second group has 400 small businesses; each needs 16 addresses.
c. The third group has 2000 households; each needs 4 addresses.
Design the sub-blocks and give the slash notation for each sub-block. Find out how many addresses are still available after these allocations.
a. For 128 addresses we use /25 mask. 255.255.255.128Group 1 has 200 medium size businesses150.80.0.0 /25 Subnet 1
150.80.0.128 /25 Subnet 2
150.80.1.0 /25….150.80.1.128 /25 Subnet 3
……..Subnet 100
--->150.80.99.128 /25 upto 150.80.99.255
Next address is 150.80.100.0
b. Group 2 has 400 small businesses, each needs 16 addresses…..we use /28 mask or 255.255.255.240150.80.100.0 /28 Subnet 1
150.80.100.16 /28 Subnet 2
150.80.100.240 /28 Subnet 16
…………150.80.124.240 /28 Subnet 400 [400/16=25]
Next address is 150.80.125.0
c. Group 3 has 2000 households each needs 4 addresses.For 4 addresses we use /30 mask or
255.255.255.252150.80.125.0 /30 Subnet 1
150.80.125.4 /30 Subnet 2
150.80.125.252 /30 Subnet 64
150.80.155.252 /30 Subnet 1984
31*64=1984
150.80.156.0 /30 Subnet 1985
150.80.156.60 /30 Subnet 2000
Next address available from 150.80.156.64
We have used 40000 addresses out of 65536 addresses. 25536 addresses remain available.
a. For 128 addresses we use /25 mask. 255.255.255.128Group 1 has 200 medium size businesses150.80.0.0 /25 Subnet 1
150.80.0.128 /25 Subnet 2
150.80.1.0 /25….150.80.1.128 /25 Subnet 3
……..Subnet 100
--->150.80.99.128 /25 upto 150.80.99.255
Next address is 150.80.100.0
b. Group 2 has 400 small businesses, each needs 16 addresses…..we use /28 mask or 255.255.255.240150.80.100.0 /28 Subnet 1
150.80.100.16 /28 Subnet 2
150.80.100.240 /28 Subnet 16
…………150.80.124.255 /28 Subnet 400 [400/16=25]
Next address is 150.80.125.0
c. Group 3 has 2000 households each needs 4 addresses.For 4 addresses we use /30 mask or
255.255.255.252150.80.125.0 /30 Subnet 1
150.80.125.4 /30 Subnet 2
150.80.125.252 /30 Subnet 64
150.80.155.252 /30 Subnet 1984
31*64=1984
150.80.156.0 /30 Subnet 1985
150.80.156.64/30 Subnet 2000
We have used 40000 addresses out of 65536 addresses. 25536 addresses remain available.