Which of the following is/are restriction(s) in classless addressing?a...
Restrictions in Classless Addressing
Classless addressing is a method of allocating IP addresses that allows for more flexibility and efficient use of address space compared to traditional classful addressing. However, there are certain restrictions that need to be followed when using classless addressing.
a) The number of addresses needs to be a power of 2
In classless addressing, IP addresses are divided into smaller blocks called subnets. Each subnet is identified by a subnet mask, which determines the number of bits used to represent the network portion of the address. The remaining bits are used to represent the host portion.
One restriction in classless addressing is that the number of addresses in a subnet needs to be a power of 2. This is because the subnet mask is a binary value, and the number of bits used to represent the host portion must be a power of 2. For example, if a subnet has 8 addresses, it would require 3 bits to represent the host portion (2^3 = 8).
b) The mask needs to be included in the address to define the block
Another restriction in classless addressing is that the subnet mask needs to be included in the address to define the block. In classful addressing, the network portion of the address is determined by the class of the address (A, B, or C). However, in classless addressing, the network portion can vary depending on the subnet mask.
By including the subnet mask in the address, it is possible to determine the network portion and the host portion of the address. This allows for more efficient routing and allocation of IP addresses.
c) The starting address must be divisible by the number of addresses in the block
In classless addressing, the starting address of a subnet must be divisible by the number of addresses in the block. This ensures that the addresses within the block are contiguous and do not overlap with other subnets.
For example, if a subnet has 16 addresses, the starting address must be divisible by 16. This guarantees that the addresses from the starting address to the starting address + 15 are assigned to the subnet.
In conclusion, the restrictions in classless addressing include the number of addresses needing to be a power of 2, the inclusion of the subnet mask in the address to define the block, and the starting address being divisible by the number of addresses in the block. These restrictions help to ensure efficient allocation and routing of IP addresses in classless addressing.