Network basics

Sergey Podgornyy
Full-Stack Web Developer at
and

 Internet, network basics. How web browsers
work?
 Client-Server Architecture. Local and remote
servers
 DNS, IP, ports and Sockets
 Hostings
 Useful utilities: ipconfig, ping, tracert, netstat
 HTTP basics. Headers, methods, responses. Most
common response statuses

The Client-server characteristic describes the
relationship of cooperating programs in an
application. The server component provides a
function or service to one or many clients, which
initiate requests for such services.

Hub Switcher Router
physical layer data link layer network layer

 HTTP – Hyper Text Transfer Protocol
 TCP - Transmission Control Protocol
 UDP - User Datagram Protocol
 IP - Internet Protocol

A web server is a computer system that
processes requests via HTTP, the
basic network protocol used to distribute
information on the World Wide Web.

 ipconfig
 ping
 traceroute (tracert)
 netstat
console application that displays all current TCP/IP network
configuration values
utility used to test the reachability of a host on an Internet
Protocol (IP) network
tool for displaying the route (path) and measuring transit
delays of packets across an Internet Protocol (IP) network
network utility tool that displays network connections for the
TCP, routing tables, and a number of network interface and
network protocol statistics

Every HTTP Request consist:
 Request string with method and HTTP version specified
 Request Headers
 An empty line
 Request Body
<Method> <URI> HTTP / <version>
GET http://example.com/index.html HTTP/1.1

HTTP defines methods to indicate the
desired action to be performed on the
identified resource.
 GET
 HEAD
 POST
 PUT
 DELETE
 TRACE
 OPTIONS
 CONNECT
 PATCH

GET /wiki/HTTP HTTP/1.1
Host: uk.wikipedia.org
User-Agent: firefox/5.0 (Linux; Debian
5.0.8; en-US; rv:1.8.1.7)
Gecko/20070914
Firefox/2.0.0.7
Connection: close
Request body

 1xx Informational
 2xx Success
 3xx Redirection
 4xx Client Error
 5xx Server Error

 200 OK
 301 Moved Permanently
 400 Bad Request
 401 Unauthorized
 403 Forbidden
 404 Not Found
 405 Method Not Allowed
 408 Request Timeout
 500 Internal Server Error
 502 Bad Gateway
 504 Gateway Timeout

The response message consists of the
following:
 A status line which includes the status
code and reason message
 Response header fields
 An empty line
 An optional message body

 Server - A name for the server
Server: Apache/2.4.1 (Unix)
 Last-Modified - The last modified date for the
requested object
Last-Modified: Tue, 15 Nov 1994 12:45:26 GMT
 Content-Length - The length of the response body
in octets
Content-Length: 348
 Content-Type - The MIME type of this content
Content-Type: text/html; charset=utf-8
 Date - The date and time that the message was sent
Date: Tue, 15 Nov 1994 08:12:31 GMT

 https://habrahabr.ru/post/307252/
 https://en.wikipedia.org/wiki/OSI_model
 https://en.wikipedia.org/wiki/Hypertext_Transfer
_Protocol#Request_methods
 https://en.wikipedia.org/wiki/List_of_HTTP_statu
s_codes
 https://en.wikipedia.org/wiki/List_of_HTTP_head
er_fields#Request_fields

Network basics

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