3. Also known as hardware/physi cal address Customer Computer (Client) Internet Service Provider (ISP) MAC Address Each Computer has: Given by NIC card IP Address Each subscriber has an unique IP assigned by ISP DHCP server assigns IP to clients on network (not unique) URL is sent to DNS Server DNS Server returns IP Address Physical Layer: hardware and turns binary code into pulses Data Link Layer: identifies devices on the Physical layer Network Layer: moves packets between computers on different networks Transport Layer: breaks data down into manageable chunks Session Layer: manages connections between machines Presentation Layer: (encryption) hides the differences among various computer systems Application Layer: provides tool for programs to use to access the network (and the lower layers) OSI Model (see notes below) OSI Model (see notes below)

4. Internet: an electronic communications network that connects networks and organizational computer facilities around the world - http://www.merriam-webster.com/dictionary/internet Switch – a device that filters and forwards traffic based on some criteria. A bridge and a router are both switches LAN – Local Area Networks WAN – Wide Area Networks

5. YourCompany.com Server TCP/IP – a set of communication protocols developed by the U.S. Department of Defense that enables dissimilar computers to share information over a network HTTP – extremely fast protocol used for network file transfers on the World Wide Web IP finds specific port Server returns webpage using Physical Layer: hardware and turns binary code into pulses Data Link Layer: identifies devices on the Physical layer Network Layer: moves packets between computers on different networks Transport Layer: breaks data down into manageable chunks Session Layer: manages connections between machines Presentation Layer: (encryption) hides the differences among various computer systems Application Layer: provides tool for programs to use to access the network (and the lower layers) OSI Model (return of webpage to user) OSI Model (return of webpage to user)