IS-IS Networking Protocol

C

The correct answer to this question is A. IS-IS PDUs are also known as LSAs.

IS-IS (Intermediate System to Intermediate System) is a link-state routing protocol used to exchange routing information between routers in a network. It is commonly used in large enterprise networks and internet service provider (ISP) networks.

IS-IS uses a hierarchical addressing scheme, where each router in the network is assigned a unique network address, similar to an IP address. The network is divided into areas, with each area containing a group of routers that share common characteristics, such as geographic location or network topology.

IS-IS routers exchange information using a type of packet known as a Protocol Data Unit (PDU), which is also called a Link State Advertisement (LSA). The PDU contains information about the router's network topology and routing information. The LSAs are flooded throughout the network, so that each router has a complete view of the network topology.

Answer A is correct because IS-IS PDUs are indeed also known as LSAs. LSAs are the packets that carry information about the router's network topology and routing information. These LSAs are flooded throughout the network, so that each router has a complete view of the network topology.

Answer B is incorrect because IS-IS PDUs are actually transmitted at Layer 2, not Layer 3. IS-IS uses the Data Link Layer (Layer 2) to communicate between routers, using the MAC address of the router's interface.

Answer C is incorrect because IS-IS routers can run multiple routing algorithms simultaneously. For example, an IS-IS router may run both an IP routing algorithm and a Multi-Protocol Label Switching (MPLS) routing algorithm.

Answer D is also incorrect because IS-IS PDUs are not hosts that send and receive packets. PDUs are packets that are sent between routers to exchange routing information, not hosts.