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.

********************

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

Computer networks multiple choice questions with answers 08

Computer networks multiple choice questions with answers, entrance exam quiz questions on computer networks, solved exam questions on computer networks, MCQ in CN

Computer Networks MCQ - SET 08

1. What are the types of acknowledgements (ACKs) used in typical TCP implementation?

(a) Selective ACKs only

(b) Both selective and cumulative ACKs

(c) Both positive and negative ACKs

(d) Positive, cumulative, selective and lookahead ACKs

Click here to view answer and explanation

Ans : (d)

Answer: (d) Positive, cumulative, selective and lookahead ACKs TCP is a connection-oriented protocol. It guarantees delivery of data and also guarantees that packets will be delivered in the same order in which they were sent. It uses acknowledgements to ensure the integrity of the data flow. Positive ACK: acknowledgement to the sender on correctly received packets. Cumulative ACK: acknowledgement on reception of data packets with the sequence number of highest in-order data received. Selective ACK: acknowledgement that indicates the sequence number of every data packet received. Lookahead ACK: the use of sequence number used as acknowledgement number.

 

2. What would be the approximate transmission time a 10 Mbps (Megabits per second) Ethernet LAN take to send a 1200 byte data packet?

(a) 1 ms

(b) 2 ms

(c) 5 ms

(d) 10 ms

Click here to view answer and explanation

Ans : (a)

Answer: (a) 1 ms Packet transmission time can be calculated as follows; Transmission time = Packet size (in bits) / Transmission rate (in bits/s) For this question; Transmission time = (1200 * 8 bit) / (10 * 106 bits/sec) = 0.00096 sec ≈ 1 ms.

 

3. Internet Message Access Protocol (IMAP) runs between email

(a) sender’s mail client and sender’s outgoing mail server

(b) receiver’s mail client and receiver’s incoming mail server

(c) sender’s mail server and receiver’s mail server

(d) sender’s mail client and receiver’s mail client

Click here to view answer and explanation

Ans : (b)

Answer: (b) receiver’s mail client and receiver’s incoming mail server IMAP was designed with the goal of permitting complete management of an email box by multiple email clients, therefore clients generally leave messages on the server until the user explicitly deletes them. Whenever you check your inbox, your email client contacts the server to connect you with your messages. When you read an email message using IMAP, you aren’t actually downloading or storing it on your computer; instead, you are reading it off of the server. As a result, it’s possible to check your email from several different devices without missing a thing. [Refer here for more]

 

4. Let us suppose that all of the network sources occasionally have data to send over the network. Which of the following would be most suitable for such a scenario?

(a) Circuit switching

(b) Packet switching

(c) Both circuit and packet switching

(d) Neither of them is true

Click here to view answer and explanation

Ans : (b)

Answer: (b) Packet switching Packet-switching is better here because there are statistical multiplexing gains – when a source does not have data to send, it will not be allocated bandwidth (that would be idle). Hence this bandwidth is available for use by other sources.

 

5. Which among the following protocols has out-of-band control messages?

(a) HTTP

(b) TCP

(c) SMTP

(d) FTP

Click here to view answer and explanation

Ans : (d)

Answer: (d) File Transfer Protocol (FTP) Out-of-band control is a characteristic of network protocols with which data control is regulated. Out-of-band control passes control data on a separate connection from main data. Protocols such as FTP use out-of-band control. FTP handles control information in one connection and the data files in the other. HTTP, TCP and SMTP have in-band control messages. It means that control message and data messages may be interleaved with each other on the same connection.

 

********************

Related links

 

• Computer Networks MCQ home page

 

Why do we use ACK in TCP?

Why packet switching is better than circuit switching for the network resources that send occasionally?

Define Internet Message Access Protocol (IMAP)

How to calculate the transmission time required to send a data packet over network?

Multiple choice questions in computer networks