HTTP

Question 1

What is HTTP( HyperText Transfer Protocol)?

Answer 1

A networking protocol that runs over TCP/IP and governs communication between web browsers and web servers

Question 2

What is TCP/IP?

Answer 2

A protocol suite that governs how data packets are transferred over the internet from one machine to another

Question 3

What is a DNS lookup?

Answer 3

Sending the domain name to the local DNS and getting back the IP address of the web server hosting the domain name.

Question 4

When is a DNS lookup performed?

Answer 4

Before HTTP communication begins.

Question 5

What is an HTTP request?

Answer 5

A message sent from the web browser to the web server.

Question 6

What is an HTTP response?

Answer 6

A message sent from the web server back to the web browser in response to an HTTP request.

Question 7

What are HTTP response/requests composed of?

Answer 7

• Start Line
• Header Field
• Blank Line
• Message Body

Question 8

What is contained in an HTTP request / response start line?

Answer 8

specifies the HTTP version being used.
- A request’s start line includes a request type and path
- A response’s start line includes a status code and phrase.

Question 9

What is contained in an HTTP request Header Field?

Answer 9

• Hostname
• Browser Identifier

Question 10

What is contained in an HTTP response Header Field?

Answer 10

• # of Bytes in message Body
• Media type of message body
• Datetime of response
• Datetime resource was last modified
• Web Server software identifier

Question 11

What is contained in an HTTP request / response Message Body?

Answer 11

Contains data being transferred between a web browser and web server.
- In a request, the message body may be empty or contain submitted form data.
- In a response, the message body may contain the requested resource.

Question 12

Where would one find a list of currently active HTTP Headers?

Answer 12

Internet Assigned Numbers Authority(IANA)

Question 13

What are the most common HTTP Request Methods?

Answer 13

• GET
• HEAD
• POST
• PATCH
• PUT
• DELETE

Question 14

What are the most common HTTP Response Status Codes?

Answer 14

• 200: Ok
• 301: Moved Permanently
• 302: Found
• 304: Not modified
• 403: Forbidden
• 404: Not Found
• 500: Internal Server Error

Question 15

What is a Browser Cache?

Answer 15

An area on the computer’s file system where web content can be stored by the web browser for quick retrieval later

Question 16

What is an Entity Tag (ETag)?

Answer 16

An identifier for a specific version of a web resource

Question 17

What is the HTTP Header “If-None-Match”?

Answer 17

Compares the provided Etag to the Etag of the resource

Question 18

What is the HTTP Header “If-Modified-Since”?

Answer 18

Request the web server only send the requested resource if the resource has changed since the specified date/time.

Question 19

What is the HTTP Header “Expires”?

Answer 19

Contains a date/time indicating when the requested resource is considered “stale”.

Question 20

What is the HTTP Header “Cache-Control”?

Answer 20

Used to specify a number of caching directives.

Question 21

What are common browser caching methods?

Answer 21

• If-None-Match
• If-Modified-Since
• Expires
• Cache-Control

Question 22

What is the difference between HTTP and HTTPS?

Answer 22

HTTPS encrypts HTTP traffic between a browser and web server so a network sniffer cannot intercept sensitive information in the HTTP traffic like passwords, credit card numbers, financial transactions, etc.

Question 23

What is the Transport Layer Security (TLS) protocol?

Answer 23

Protocl used in HTTPS which uses asymmetric public keys to encrypt data between the browser and web server.

Question 24

What is a network sniffer?

Answer 24

Software that monitors network traffic and allows users to inspect HTTP requests and responses.