1. Presented by Rebecca Meinhold But How Does the Internet Work?

2. Let’s get started with the basics

3. First thing you need to know is that every computer has an IP address There are TWO ways in which a computer gets an IP address: A computer administrator will manually set the IP address to the machine The Dynamic Host Control Protocol (DHCP) server is responsible for assigning IP addresses to all computers on the network

4. There are two different types of IP addresses

5. Your computer Your router/ domain name server Google’s IP address A request is sent to the router to find out the IP address of the domain name Here is where the domain name is converted into it’s IP address Once the IP is known, the DNS server sends an HTTP GET request to Google’s particular IP google.com 74.125.224.72 HTTP GET request

6. MAC addresses are added in the data link layer before the packet heads to the physical layer In the network later, information related to source & destination IP addresses are are added and then are sent to the Data Link layer Application Layer Presentation Layer Session Layer Transport Layer Network Layer Data Link Layer Physical Layer HTTP GET request Packet Requests are encapsulated in the form of transport layer packets and then are sent to the network layer

7. Two protocols operate in the Transport Layer: UDP TCP User Datagram Protocol Transmission Control Protocol Ensures that the packet is not larger than the largest protocol data unit in the path located between your computer and the destination Offers a limited amount of service when messages are exchanged between computers in a network that uses IP

8. The router searches it’s cache for the packets host address, when found, it forwards the packet to it’s destination Packet Your computer Router Destination Packet When the packet leaves your computer, the MAC Address of the router in which your packet is being transferred to is used as the packets destination MAC Address

9. The following slide will show the process that the packet goes through while traveling to it’s destination

10. HTTP GET Request is passed to the application listening on the port Application Layer Presentation Layer Session Layer Transport Layer Network Layer Data Link Layer Physical Layer Packet IP address checks and check-sum verifications are done before passing to the transport layer The MAC address is checked to see if the packet is at the correct destination

11. The response is then formed and transmitted back in the same way that it came in