An organization requires a range of IP addresses to assign one to each...
Concept:
CIDR stands for Classless Inter Domain Routing. CIDR denotes the number of bits in the Netid. Upon subnetting, any IP address consist of three subparts: Netid (bits for identifying the network), subnetid (bits for subnetting), and Hostid (bits for address allocation to hosts)
Calculation:
Given CIDR is 17, that means Netid=17.
There are 1500 devices, so the number of bits in Hostid= 11 (because 211 ≥ 1500)
Therefore, subnet bits= 32- (17+11) = 4
Hence, in any IP address in the given network, first 17 bits be part of network, next 4 of subnet ans last 11 bits would be for host address. Host bits should be all 0s
Address I: Cannot be allotted
202.61.84.0/21= 202.61. 0 1010 100.00000000. This address is not possible because the all the 11 host bits should be zero, but it contains a 1.
Address II: Can be allotted
202.61.104.0/21= 202.61. 0 1101 000.00000000. This address is possible as all the host bits are 0 and network bits are also satisfied.
Address III: Can be allotted
202.61.64.0/21= 202.61.0 1000 000.0000000. This address is possible as all the host bits are 0 and network bits are also satisfied
Address IV: Cannot be allotted
202.61.144.0/21= 202.61. 1 0010 000. 00000000. This address is not possible because bit in Netid has become 1.