HTTP:The Postal Service of the Internet

Question 1

Define protocol

Answer 1

standard for communication between machines

Question 2

What 3 protocols are used in most web communication

Answer 2

HTTP, TCP/IP, DNS

Question 3

Define HTTP

Answer 3

(Hypertext Transfer Protocol) High-level web communication. Transfers files such as HTML, CSS, JavaScript, images, and form submissions. Designates how requests and responses should be structured.

Question 4

Define TCP/IP

Answer 4

Transmission Control Protocol (TCP) and the Internet Protocol (IP) Low-level web communication for transferring small bits of raw data aka packets

Question 5

What is DNS?

Answer 5

Domain Name Service: Address book for the internet. Translates human friendly names into server addresses

Question 6

How does HTTPS differ from HTTP?

Answer 6

HTTP protocol with a secure connection. Can’t be read in-transit due to encryption.

Question 7

Describe the use of packets for transmitting files

Answer 7

Files are broken down into small, standardized chunks of information that are sent and reassembled after reaching their destination

Question 8

What purpose do domain names serve?

Answer 8

ex: www.launchcode.org

This name is an alias for server IP address

Question 9

Define IP address

Answer 9

numerical label assigned to each device connected to a computer network

Question 10

What does it mean to resolve an address?

Answer 10

When a message is addressed to domain name, a lookup is performed on a name server. The message is sent to corresponding IP

Question 11

Define nameserver

Answer 11

Directory of domains and IP addresses

Question 12

What is a loopback address?

Answer 12

Alias localhost. Special IP address 127.0.0.1 used by computer to refer to itself

Question 13

Define URL

Answer 13

Uniform resource locator aka web addresses.

Question 14

Write a common URL structure

Answer 14

scheme://host:port/path?query_string

Question 15

Describe scheme

Answer 15

Most often specifies protocol used in making request. Common ones include: http, https, ftp, mailto, file

Question 16

What function does Host serve in a URL?

Answer 16

portion of URL specifying when request should be sent. Can be IP or domain

Question 17

Are Port Numbers required in a URL? What function do they serve?

Answer 17

Optional in URL. Port determines specific application on server that should handle request. Conventionally given type of app always uses same port (ex: MySQL uses port 3306). If none specified, default value used based on scheme (http:// is 80, https:// is 443)

Question 18

Define Path

Answer 18

Tells server what is being requested. If no path specified, root path / is used

Question 19

What function does a Query String serve?

Answer 19

Provides additional data needed to fulfill request

Question 20

Top level domain (TLD)

Answer 20

.com, .org, .net - categories of internet, help sort websites and route requests through certain group of servers

Question 21

What symbol is used for a Fragment, and what role does it play in a URL

Answer 21

Can mark specific spots on a web page, among other things

Question 22

What role does % Encoding serve in a URL

Answer 22

Help encode special characters in URL

Question 23

Describe the role of routers in transmitting data

Answer 23

Direct packets of information around the internet. Each time packet encounters a router it’s IP address is added to server request. Server sends back along same path.

Question 24

What kind of data do requests contain?

Answer 24

• URL requested
• method
• metadata - browser, type of data
• optional request msg

Question 25

What kind of data do responses contain?

Answer 25

Status line with response code, response headers, blank line, response body

Question 26

List the categories of response codes

Answer 26

1xx (Informational): The request was received but processing has not finished
2xx (Successful): The request was valid and the server successfully responded
3xx (Redirection): The client should go elsewhere to access the requested resource
4xx (Client Error): There was a problem with the client’s request
5xx (Server Error): The client’s request was valid, but the server experienced an error when fulfilling it

Question 27

Describe the HTTP Response Code 200

Answer 27

The requested resource exists and was successfully returned

Question 28

Describe the HTTP Response Code 301

Answer 28

The requested resource has moved, and the client should look for it at the URL included in the Location header.

Question 29

Describe the HTTP Response Code 404

Answer 29

The server received the request, but the requested resource does not exist on the server.

Question 30

Describe the HTTP Response Code 500

Answer 30

The server experienced an error while fulfilling the request

Question 31

Describe the HTTP Response Header Content-Type

Answer 31

The type of data included in the response body. Examples: text/html, text/css, image/jpg

Question 32

Describe the HTTP Response Header Content-Length

Answer 32

The size of the response body in bytes.

Question 33

Describe the HTTP Response Header Location

Answer 33

The URL that the client should visit to find a relocated resource.

Question 34

In developer tools the ____ tab displays all HTTP requests and responses used to load a page. Only tracks the data if page is open during the request

Answer 34

Network