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CCNA® Cisco Certified Network Associate: Study Guide, Seventh Edition by Todd Lammle

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Exam Essentials

Describe the benefits of Variable Length Subnet Masks (VLSMs). VLSMs enable the creation of subnets of specific sizes and allows the division of a classless network into smaller networks that do not need to be equal in size. This makes use of the address space more efficient as many times IP addresses are wasted with classful subnetting.

Understand the relationship between the subnet mask value and the resulting block size and the allowable IP addresses in each resulting subnet. The relationship between the classful network being subdivided and the subnet mask used determines the number of possible hosts or the block size. It also determines where each subnet begins and ends and which IP addresses cannot be assigned to a host ...

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