Explanation/Reference:
Section: Enterprise Network Design Explanation
Explanation:
You should not use Routing Information Protocol version 1 (RIPv1) or Interior Gateway Routing Protocol (IGRP) to implement the subnets displayed in the exhibit. The network shown in the exhibit uses variable- length subnet masking (VLSM). VLSM provides the ability to efficiently allocate addresses in an assigned address space by creating a hierarchy of subnets for a single network number.
In this scenario, the Class B network, 172.16.0.0, has been subnetted into three subnetworks:
172.16.127.0/17, 172.16.192.0/18, and 172.16.144.0/20. VLSM relies on the routing protocol to include the subnet mask in routing table updates. RIPv1 and IGRP do not support VLSM, because they do not carry subnet mask information within routing updates. Therefore, when RIPv1 or IGRP is used on a network, you must use the same subnet mask throughout the network. Routing protocols that do not support VLSM are called classful routing protocols.
RIP version 2 (RIPv2), Open Shortest Path First (OSPF), and Enhanced IGRP (EIGRP) support VLSM.
These routing protocols support VLSM because they send subnet mask information within routing updates.
VLSM enables you to use different subnet masks within the same network. Routing protocols that support VLSM are called classless routing protocols.
Reference:
CCDA 200-310 Official Cert Guide, Chapter 8, VariableLength Subnet Masks, pp. 305-307 CCDA 200-310 Official Cert Guide, Chapter 10, Classless Versus Classful Routing Protocols, pp. 385-386 Cisco: Why Don't RIPv1 and IGRP Support VariableLength Subnet Mask?