http

Question 1

What does HTTP stand for?

Answer 1

HyperText Transfer Protocol.

Question 2

What are the main roles in HTTP?

Answer 2

Client (browser) requests and displays web objects; Server sends objects in response.

Question 3

Which RFCs define HTTP/1.0 and HTTP/1.1?

Answer 3

HTTP/1.0: RFC 1945, HTTP/1.1: RFC 2068.

Question 4

What is the structure of an HTTP request message?

Answer 4

Request line (method, URL, version), header lines, and an optional entity body.

Question 5

Is an HTTP request human-readable?

Answer 5

Yes, it’s ASCII text format.

Question 6

What marks the end of an HTTP message?

Answer 6

A blank line (carriage return + line feed).

Question 7

List the common HTTP methods.

Answer 7

GET, POST, HEAD, PUT, DELETE.

Question 8

What does the GET method do?

Answer 8

Retrieves a file specified in the URL path.

Question 9

What does the POST method do?

Answer 9

Sends data enclosed in the entity body as input to the specified resource.

Question 10

What does the HEAD method do?

Answer 10

Requests headers only (no body) to check metadata.

Question 11

What does the PUT method do?

Answer 11

Uploads a file in the entity body to the path specified in the URL.

Question 12

What does the DELETE method do?

Answer 12

Deletes the file or resource specified in the URL field.

Question 13

How is input uploaded using the GET method?

Answer 13

As parameters encoded into the URL field.

Question 14

How is input uploaded using the POST method?

Answer 14

As data in the request’s entity body.

Question 15

What does a sample HTTP POST request include?

Answer 15

A request line, headers (Host, Content-type, etc.), and form data in the body (e.g., Account=…&State=…).

Question 16

What is the structure of an HTTP response?

Answer 16

Status line (version, status code, phrase), header lines, and data (body).

Question 17

Give an example of a status line.

Answer 17

HTTP/1.1 200 OK.

Question 18

List common HTTP status codes.

Answer 18

200 OK, 301 Moved Permanently, 400 Bad Request, 404 Not Found, 505 HTTP Version Not Supported.

Question 19

What does status code 200 mean?

Answer 19

Request succeeded; the requested object follows in the message.

Question 20

What does status code 301 mean?

Answer 20

The requested object has been moved; new location is in the Location header.

Question 21

What does status code 400 mean?

Answer 21

Bad Request — the message could not be understood by the server.

Question 22

What does status code 404 mean?

Answer 22

Not Found — the requested document doesn’t exist on the server.

Question 23

What does status code 505 mean?

Answer 23

HTTP Version Not Supported — the server doesn’t support the HTTP version used.

Question 24

What port does HTTP use?

Answer 24

Port 80 by default.

Question 25

What is a persistent connection in HTTP?

Answer 25

Multiple objects can be sent over one TCP connection between client and server (default in HTTP/1.1).

Question 26

What is a nonpersistent connection?

Answer 26

At most one object per TCP connection (used by HTTP/1.0).

Question 27

What are drawbacks of nonpersistent connections?

Answer 27

Requires 2 RTTs per object; browsers may open parallel TCP connections to compensate.

Question 28

What is RTT in HTTP performance?

Answer 28

Round-Trip Time — time to send a small packet to a server and back.

Question 29

What is the formula for total response time in HTTP?

Answer 29

2 × RTT + transmission time.

Question 30

Is HTTP stateless?

Answer 30

Yes, servers keep no record of past requests.

Question 31

What are cookies used for in HTTP?

Answer 31

To maintain user-server state across requests (e.g., sessions, shopping carts, recommendations).

Question 32

What are first-party cookies?

Answer 32

Cookies from the website you directly visit.

Question 33

What are third-party cookies?

Answer 33

Cookies set by domains other than the one you visited (often used for tracking).

Question 34

How can cookies be used to track users?

Answer 34

Third-party ad domains can correlate cookies across sites to track browsing behavior.

Question 35

What is a web cache or proxy server?

Answer 35

An intermediary server that stores copies of objects to reduce client response time and save bandwidth.

Question 36

What happens on a cache hit?

Answer 36

The cache returns the object directly to the client.

Question 37

What happens on a cache miss?

Answer 37

The cache requests the object from the origin server, stores it, and forwards it to the client.

Question 38

What is the purpose of a Conditional GET?

Answer 38

To ensure cached content is up-to-date while minimizing unnecessary transfers.

Question 39

What are the main drawbacks of HTTP/1.1?

Answer 39

Requests are sequential, causing backlog and delays with multiple page objects.

Question 40

How does HTTP/2 improve over HTTP/1.1?

Answer 40

Uses multiplexing — all requests share a single connection and can be processed concurrently.

Question 41

What is HTTP/2’s frame structure?

Answer 41

Frames include length, type, flags, stream ID, and data; frames are grouped into streams and messages.

Question 42

What is a stream in HTTP/2?

Answer 42

A bidirectional flow of bytes between client and server identified by a stream ID.

Question 43

What are HTTP/2’s key goals?

Answer 43

Reduce latency with multiplexing, header compression, prioritization, and server push.

Question 44

What does HTTP/3 use instead of TCP?

Answer 44

UDP-based QUIC transport protocol.