The primary networks and core routers around the world make up the backbone of the Internet and support the exchange of Internet traffic between countries, continents and across oceans. To work properly, the Internet relies on hardware and software such as servers, routers, switches and computers, wires, cables, satellites and dishes, the protocols in the TCP/IP suite, etc.
Clients
A client is a computer or a device that makes requests to a server.
Clients can be Desktops, Laptops, Tablets, Smart Phones, Apps, etc.
Servers
A server is both a piece of hardware, the computer itself and a piece of software that responds to requests. A server is typically made for production and speed.
Server examples:
- Database Servers
- DNS Servers (Domain Name Servers)
- File Servers
- Mail Servers
- Web Servers
- Gaming Servers
DNS
Domain Name Server
The DNS system is the address book of the internet. It connects domain names with IP addresses.
Servers use numbers to locate each other (i.e. IP addresses). Domain Name Servers are servers that match the domain name requested by a client with the IP address of the server hosting the requested content then forwards the request to that server. The server then sends a response back to the client.
The communication between the server and the client happen over a protocol called HTTP.
Depending on your location and time of access, you may use a different DNS to GET websites. Not all
How it works
- The DNS system looks at the TLD or .com in the case of teamtreehouse.com.
- It will then ask which server the domain teamtreehouse is on, if it doesn’t already know.
- Within DNS there’s a hierarchy of servers, so if one doesn’t know, it sends a request to the next server, and the next, until the correct website is located.
- If all goes well, the server sends a short message back to the client, saying that everything is okay (i.e. HTTP status code), followed by the web page itself.
HTTP
Hyper Text Transfer Protocol
Clients and Servers have to speak the same language in order for them to communicate. HTTP is a protocol followed in the web to GET and POST data from and to servers. HTTP is how clients and servers transfer webpages on the web.
HTTPS
The s stands for secure. It means communication between a client and a server is private and encrypted.
TCP/IP
Transmission Control Protocol / Internet Protocol.
Responsible for transmitting data efficiently on the internet (i.e. webpages, files, emails, etc.)
TCP: How
It splits data up into packets and puts them back together at their destination.
By breaking data into these small, manageable chunks, so that no single transmission dominates the pipeline. This way many users can transmit data at the same time very quickly. Each packet is designed to work independently. The directions on how to accomplish this are written in a header that wraps every TCP packet.
IP: Where
The Internet Protocol, tells the packets where to go and where they should return to.
IP Address
A unique number that identifies every computer connected to the internet. The IP protocol uses IP addresses to route the TCP packets.
In order to transmit the data to the correct location, the IP protocol also adds a small header of information to the packet (e.g. the source IP address and the destination IP address.), just like TCP.
Routers
Routers connect multiple networks. Routers are intermediary devices that route data packets destined for places outside the local network, and move them to other routers using protocols until all the data reaches its correct destination. Routers bridge the gap between computers across towns, states, and countries.
Routing Tables
Routers determines the best path (route) to send each data packet from one router to the next. Each router keeps information about other routers in what’s called a routing table.
When a packet is received, a router examines the packet and determines where it needs to go next, using the information from the routing table, which contains at least three bits of information:
- The network ID
- The cost, (i.e. how efficient the path is)
- The next gateway
Switches
A switches is a device that connects individual computers together on a local area network.
Switches are like routers, they also manage the flow of data across a network but in a slightly different way. A switch’s purpose is to physically connect devices on local networks with cables. Connecting a local network to an external network is done with a router.
LAN
A switch connecting devices together creates what’s called a local area network, or LAN.
WAN
wide area network, or WAN
Modems
Old technology devices that translate digital data from a computer into electrical signals to be transmitted over cable or telephone wires. Then an ethernet cable will connect the modem to a residential router. Today, a modem and a router are combined into one device used to connect homes to the internet.