Computer networks MCQ - Why SMTP is a 'PUSH' protocol?

Multiple choice questions in Computer Networks, What for SMTP is used? Why do we refer to SMTP as 'PUSH' protocol? What are the 'POP' mail protocols?

 

MCQ on Simple Mail Transfer Protocol

1. Which among the following protocols is an example of “push” protocol?

(a) Simple Mail Transfer Protocol (SMTP)

(b) Post Office Protocol (POP)

(c) Internet Mail Access Protocol (IMAP)

(d) Domain Name Service (DNS)

Answer: (a) Simple Mail Transfer Protocol (SMTP) Why SMTP is referred as a ‘PUSH’ mail protocol? SMTP is a push protocol; it pushes the message from the client to the server. There are two other aspects of mail delivery, though: delivering the mail to the central mail server, and sending outgoing mail. For sending an email, SMTP is used twice; to push the mail from sender to the sender's mail server, and to send the mail from source server to the destination mail server(s). As it happens, both these tasks are handled by push mail protocols, so called because the sender initiates push mail transfers. Majority of the mails delivered on the Internet uses SMTP. SMTP uses sender-push model where the sender knows the identity of a receiver in advance and pushes the message in an asynchronous manner to the receiver. The receiver accepts the entire message, may choose to optionally examine the message, and then accept or discard it. You cannot pull emails off the server using SMTP. POP and IMAP are examples of pull mail protocols.

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What for SMTP is used? 

Why do we refer to SMTP as 'PUSH' protocol? 

What are the 'POP' mail protocols?

SMTP uses sender-push traffic delivery model

Differentiate between forwarding and routing in computer networks

Difference between forwarding and routing; forwarding table, routing table, data plane, control plane

Forwarding Vs Routing

 

Both are activities that take place at a router in the Network Layer.

 

Forwarding	Routing
·        Transfers the incoming packets from input port to the appropriate output port in a router. ·        Uses the forwarding table. ·        Determines local forwarding at this router ·        Done in hardware at link speeds (very fast). ·        Also known as “data plane”.	·        Determines the route taken by the packets from source to their destination. ·        Creates the forwarding tables. ·        Determines end-to-end path through network ·        Done at time scales of minutes or hours. ·        Also known as “control plane”.

 

Forwarding refers to the router-local action of transferring packet from an input link interface to the appropriate output link interface.

A forwarding table usually needs to be structured to optimize the process of looking up an address when forwarding a packet, which holds more information such as MAC address.

 

Routing refers to the network-wide process that determines the end-to-end paths that packets take from source to destination.

The routing table usually focuses on calculating changes in topology, and the entries in routing table are usually more succinct, only including the IP of next hop.

 

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Related links

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Find the key differences between forwarding and routing

What is forwarding table

What is routing table