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sudo apt-get install avahi-daemon

Introduction

1)     When using the internet most people connect to websites or other internet servers by connecting to a domain name, as in “michaelerik.duckdns.org”. Internet applications, though, do not communicate via domain names, but rather uses IP address such as 10.66.12.104.

IP Address – Every machine on the Internet has a unique IP address. A server has a static IP address that does not change very often. An IP is a unique string of numbers separated by periods that identifies each computer using the Internet to communicate over a network, we can also refer to it as our postal code.

Example of this is: 10.66.12.104

When you enter a URL into your Web browser, the user’s local host file is first checked to resolve the DNS to an IP address. If this does not happen, it then moves to the second checkpoint.

2) When you type a domain name in your program that you wish to connect to, your application must first convert it to an IP address that it will use to connect to. The way these hostnames are resolved to their mapped IP address is called Domain Name Resolution (DNS). Think of it like our computers GPS for the internet.

Computers and other network devices on the Internet use an IP address to route your request to the site you're trying to reach. This is similar to dialing a phone number to connect to the person you're trying to call. Thanks to DNS, though, you don't have to keep your own address book of IP addresses. Instead, you just connect through a domain name resolution, also called a DNS server or name server, which manages a massive database that maps domain names to IP addresses

When you enter a URL into your Web browser, your DNS server uses its resources to resolve the name into the IP address for the appropriate Web server. A DNS is the task of converting domain names to their corresponding IP address. This is all done behind the scenes and all operating systems have the below default order for domain name resolution.

1. (OS) – Host Files: (which resides on your local computer/device) NOTE: This has already happened and if not resolved the second checkpoint happens.

2. (Router) – DNS Gateway: can always override DNS to where it needs to be (ex. Rogers modem)

3. (Internet) – Registrar: (example go daddy) NOTE: This happens if not resolved in 1 or 2.

The browser communicated with a name server to translate the server name " michaelerik.duckdns.org” nto an IP Address, which it uses to connect to the server machine. The browser then formed a connection to the server at that IP address on port 80.

Your browser formed a connection to a Web server, requested a page and received it.

The browser broke the URL into three parts:

• The protocol ("http")
• The server name ("www.howstuffworks.com")
• The file name ("web-server.htm") 

The server then sent the HTML text for the Web page to the browser.

The browser read the HTML tags and formatted the page onto your screen.

(Browser Cache- keeps a memory of what you have looked at, it’s helpful because you don’t need to download again and it’s a default setting in the computer that captures what you have looked at. So as you start to type a few characterises pages will automatically start to populate until you find what you’re looking for. Sometimes you have to force cache request (control r) or delete cache. To be able to see updated page content.)

3)     Any server machine makes its services available to the Internet using numbered ports, one for each service that is available on the server. For example, if a server machine is running a Web server and an FTP server, the Web server would typically be available on port 80, and the FTP server would be available on port 21. Clients connect to a service at a specific IP address and on a specific port.

 Here are some common port numbers:

• tp 21
• telnet 23
• smtp 25 (Simple Mail Transfer, meaning e-mail)
• time 37
• nameserver 53
• gopher 70
• finger 79
• www 80

Process

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