IP and MAC Addresses, DNS Servers Component 1 IP and MAC Addresses, DNS Servers

Starter: Pre-Reading Recap MAC addresses? What are MAC addresses used for? IP Addresses? What does IP stand for What is IP addressing used for Why do IP addresses not contain any numbers higher than 255 What is the difference between a MAC address and an IP address? What is a DNS Server? Explain how a DNS Server works What are the advantages of using a DNS Server?

Learning intentions and outcomes To develop an understanding of how devices are addressed on a network To develop an understanding of how DNS servers are used when browsing the Internet Learning Outcomes: Explain how Domain Name System (DNS) servers and Internet Protocol (IP) addresses work

IP Addresses IP is short for Internet Protocol. A 'protocol' is a set of rules for doing something. In this case it is the task of being able to uniquely identify every computer connected to an IP based network. The way this is done is to assign a long number to each computer made up of 4 bytes. This normally takes the form of four, three digit numbers separated by a dot. Like this 255.168.101.004 An IP address is an address, which is allocated to a computer system on a network, usually by a DHCP (Dynamic Host Configuration Protocol) server. Alternatively, you may assign your own IP address if you do not wish to rely on the services of a DHCP server.

IP Addresses It is used to uniquely identify computer systems on a network, thus allowing communication between them. In routing tables, the corresponding IP address of a unique MAC address is stored and updated as necessary.

Graded Exercises Complete the Grade 4 exercises on IP Addresses Remember to be smart when using the Internet: Wikipedia is often complicated – sometimes even I don’t understand! BBC Bitesize, Teach ICT, and Revision World are better places to find your information!

MAC Addresses A MAC address (media access control address), also known as a physical address or a hardware address, is a unique hexadecimal number given to any communication device, such as a network interface card. The code identifies the card and also the maker of that card. It is a 48 bit binary number stored within the card hardware itself. To make it a bit more people friendly the MAC address is usually quoted as a set of six hex number like this: MAC address: 0A-14-FF-32-11-23-97

MAC Addresses The address is usually stored in a communication devices’ ROM. Hexadecimal notation is used as it allows for over 281 trillion different combinations of MAC address. Routing tables store the MAC address of communication devices on its network, as the address is permanent and does not change like an IP address. A computer system can have multiple network interface cards, each with its own unique MAC address.

IP vs MAC Addresses An IP Address is the location of the device on the network. A MAC address is the unique address of the device. They are different things!

Graded Exercises Complete the Grade 4 exercises on MAC Addresses Remember to be smart when using the Internet: Wikipedia is often complicated – sometimes even I don’t understand! BBC Bitesize, Teach ICT, and Revision World are better places to find your information!

DNS Servers A Domain Name System (DNS) is a distributed database that matches IP addresses to computer system resources. One example of this is to match an IP address to a human friendly domain name. For example, if you wanted to visit the Google search engine, the computer system on which the website is stored has an IP address assigned to it; 173.194.34.191

DNS Servers To access google you tend to type in www.google.com but you could enter the IP address manually! When you type www.google.com your computer system sent a request to its DNS server for the IP address that is mapped to the domain name www.google.co.uk. The DNS server returned the IP address 173.194.34.191, which allows your computer system to communicate with the computer system where the Google search engine is stored

DNS Servers: What’s the point? Why do you think we have DNS Servers? Which is easier to remember? Why?

DNS Server Levels There are many different DNS servers located across the world. If your local DNS server does not store the address of the resource you are requesting, it will pass the request along to another higher level DNS server (for example your Internet Service Providers DNS Server) If again the address is not found, you ISPs DNS server will pass the request on to a higher level DNS server which may be the DNS server responsible for an entire zone, such as the .co.uk zone.

DNS Server Levels

DNS Server: Other uses Another example where a DNS server is used is where a computer system, on joining a network, would query the DNS server for the IP address of other useful computer systems, such as the logon server, which stores the details of all usernames and passwords.

Graded Exercises Complete the Grade 4 exercises on DNS Servers Remember to be smart when using the Internet: Wikipedia is often complicated – sometimes even I don’t understand! BBC Bitesize, Teach ICT, and Revision World are better places to find your information!

Grade 5 Exercises Complete the Grade 5 Exercises to demonstrate that you can apply your knowledge of IP Addresses, MAC Addresses, and DNS Servers Remember to be smart when using the Internet: Wikipedia is often complicated – sometimes even I don’t understand! BBC Bitesize, Teach ICT, and Revision World are better places to find your information!

Crib Sheet – What I must remember about _______ Starting Point: Read the learning outcomes from the exam board Record the key facts that you need to remember about IP Addresses, MAC Addresses, and DNS Servers. Think about what you have learnt today, what questions you have been asked, definitions of words, or anything else you think is important!

Homework Question Sheets: Pre-reading notes: Q40 – Network Communication Pre-reading notes: 31-35 (Protocols, TCP/IP 5 Layer Protocol, Email Protocols)