HTTP Flashcards
What is HTTP( HyperText Transfer Protocol)?
A networking protocol that runs over TCP/IP and governs communication between web browsers and web servers
What is TCP/IP?
A protocol suite that governs how data packets are transferred over the internet from one machine to another
What is a DNS lookup?
Sending the domain name to the local DNS and getting back the IP address of the web server hosting the domain name.
When is a DNS lookup performed?
Before HTTP communication begins.
What is an HTTP request?
A message sent from the web browser to the web server.
What is an HTTP response?
A message sent from the web server back to the web browser in response to an HTTP request.
What are HTTP response/requests composed of?
- Start Line
- Header Field
- Blank Line
- Message Body
What is contained in an HTTP request / response start line?
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.
What is contained in an HTTP request Header Field?
- Hostname
- Browser Identifier
What is contained in an HTTP response Header Field?
- # of Bytes in message Body
- Media type of message body
- Datetime of response
- Datetime resource was last modified
- Web Server software identifier
What is contained in an HTTP request / response Message Body?
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.
Where would one find a list of currently active HTTP Headers?
Internet Assigned Numbers Authority(IANA)
What are the most common HTTP Request Methods?
- GET
- HEAD
- POST
- PATCH
- PUT
- DELETE
What are the most common HTTP Response Status Codes?
- 200: Ok
- 301: Moved Permanently
- 302: Found
- 304: Not modified
- 403: Forbidden
- 404: Not Found
- 500: Internal Server Error
What is a Browser Cache?
An area on the computer’s file system where web content can be stored by the web browser for quick retrieval later
What is an Entity Tag (ETag)?
An identifier for a specific version of a web resource
What is the HTTP Header “If-None-Match”?
Compares the provided Etag to the Etag of the resource
What is the HTTP Header “If-Modified-Since”?
Request the web server only send the requested resource if the resource has changed since the specified date/time.
What is the HTTP Header “Expires”?
Contains a date/time indicating when the requested resource is considered “stale”.
What is the HTTP Header “Cache-Control”?
Used to specify a number of caching directives.
What are common browser caching methods?
- If-None-Match
- If-Modified-Since
- Expires
- Cache-Control
What is the difference between HTTP and HTTPS?
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.
What is the Transport Layer Security (TLS) protocol?
Protocl used in HTTPS which uses asymmetric public keys to encrypt data between the browser and web server.
What is a network sniffer?
Software that monitors network traffic and allows users to inspect HTTP requests and responses.
