Question

Choose two applications from the list below. You should make your selections so that you are able to describe both points of similarity and points of difference when answering the questions that follow.

• Electronic file transfer

• Electronic mail

• Bit-torrent

• Internet Relay Chat (IRC)

• The Domain Name System (DNS)

• IP Telephony (VoIP, not Skype or Facetime, etc.)

• Real-time streaming (Not web-based solutions such as Youtube, Facebook, Instagram, etc.)

Answer the following questions about both of your chosen applications.

a) What application-layer protocol do each of your applications use? (If either of your applications use more than one protocol, decide which protocol is the main one)

b) Give a brief summary of what each of your protocols does in relation to the application. (2-3 lines for each protocol)

c) Which transport layer protocol(s) does each of your application layer protocols use?

Answer 1

1. Electronic File Transfer :

   1. This application uses file transfer protocol(ftp) to transfer files.

   2. FTP is used to transfer file between local and remote file system electronically. FTP opens two connections namely, data connection and control connection between the two systems. Data connection is to transfer data and control connection is to send and receive instructions.

   3. FTP works above TCP(Transmission Control Protocol) of transport layer.

2. Electronic Mail:

   1. This application uses Simple Mail Transfer Protocol(SMTP) to send mail while Post Office Protocol(POP) or Internet Mail Access Protocol(IMAP) is used to retrieve mail from mail server. SMTP can be considered as main protocol involved.

   2. SMTP is an application layer protocol. The client who sends the mail opens a connection to the SMTP server and then sends the mail across the connection. The SMTP server is always on listening mode. As soon as it listens for a connection from any client, the SMTP process initiates a connection. After successfully establishing the connection the client sends the mail instantly.

   3. SMTP operates over TCP of transport layer.