Unreliable EIGRP Packet Types
Question
Which two EIGRP packet types are considered to be unreliable packets? (Choose two.)
Answers
Explanations
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EIGRP (Enhanced Interior Gateway Routing Protocol) is a distance-vector routing protocol that is commonly used in computer networks to share routing information between routers. EIGRP packets are classified into five types: hello, acknowledgment (ACK), update, query, and reply.
Out of these five packet types, only the query and reply packets are considered to be unreliable packets. The reasons for this are as follows:
- Query Packets: EIGRP routers use query packets to request routing information from their neighbors when they are unable to find a route to a specific network. Query packets are sent out as multicast packets to all EIGRP neighbors. If a router receives a query packet, it will look for the requested information in its own routing table and forward the query to its own neighbors if it doesn't have the information.
Query packets are considered unreliable because they do not contain any sequence numbers, which means that there is no way to detect duplicate queries. This can lead to unnecessary network traffic and delay in finding the required routing information.
- Reply Packets: EIGRP routers use reply packets to respond to query packets. Reply packets contain the requested routing information and are sent back to the router that sent the query packet. Like query packets, reply packets are also sent as multicast packets to all EIGRP neighbors.
Reply packets are considered unreliable because they also do not contain any sequence numbers. This means that there is no way to detect duplicate replies. If a router receives multiple replies for the same query, it may choose the wrong route, which can lead to routing loops and other network issues.
On the other hand, hello, acknowledgment (ACK), and update packets are considered reliable packets because they contain sequence numbers. Sequence numbers are used to ensure that packets are delivered in the correct order and to detect duplicate packets.
In summary, the two EIGRP packet types that are considered to be unreliable packets are query and reply packets.
