Application layer

Question 1

What is application layer for?

Answer 1

It provides an interface for user applications and communication service processes to exchange data between end devices.

Question 2

Name a few application layer protocols?

Answer 2

HTTP, SSH, MQTT, HTTPS, SMTP, IMTP, FTP, list goes on…

Question 3

What does HTTP stands for and where is it used?

Answer 3

HyperText Transfer Protocol. Most notably WWW uses HTTP/HTTPS

Question 4

Whats the difference between HTTP and HTTPS?

Answer 4

HTTPS uses Transport Layer Security for encryption. (S after HTTP stands for Secure)

Question 5

Describe client-server model?

Answer 5

One device requests data (client) from the remote service (server)

Question 6

Name HTTP request methods:

Answer 6

GET, HEAD, POST, PUT, DELETE, CONNECT, OPTIONS TRACE

Question 7

What protocol was created to avoid problems caused by HTTP application polling?

Answer 7

WebSocket

Question 8

What is FTP?

Answer 8

File Transfer Protocol, that uses TCP and lack encryption.

Question 9

What is DNS?

Answer 9

Domain Name System

Question 10

What is it used for?

Answer 10

It is used for storing deviced names and their IP addresses. It’s a ditributed database.

Question 11

Tell example of ccTLD and gTLD, also tell what they are?

Answer 11

.fi .ee and such are country code Top Level Domains, while .com, .net, .org are generic Top Level Domains

Question 12

What does SSH stand for and what’s it used for?

Answer 12

Secure Shell, Its a secure, open source remote connection protocol