1. What is an IP Address An IP Address (or Internet Protocol address) is an address used to uniquely identify a device on an IP network. The address is made up of 32 binary bits which can be divisible into a network portion and host portion with the help of a subnet mask. www.nyu.edu = 128.122.108.71 = 10000000.01111010.01101100.01000111 The 32 binary bits are broken into four octets (1 octet = 8 bits). Each octet is converted to decimal and separated by a period (dot). For this reason, an IP address is said to be expressed in dotted decimal format.

2. Network (or Subnet) Masks A network mask helps you know which portion of the address identifies the network and which portion of the address identifies the node. Class A, B, and C networks have default masks, also known as natural masks, as shown below. Class A: 255.0.0.0 (or 11111111.00000000.00000000.00000000) Class B: 255.255.0.0 (or 11111111.11111111.00000000.00000000) Class C: 255.255.255.0 (or 11111111.11111111.11111111.00000000) Default Network - The IP address of 0.0.0.0 is used for the default Loopback - IP address 127.0.0.1 is used by the host computer to send a message back to itself for troubleshooting and network testing.

3. IPv4 and IPv6 Traditional IP addresses are 32-bits long and written in dotted decimal format. These are considered IPv4 format addresses. 172.17.100.203 Since there are only approximately 4.2 billion public IPv4 addresses available (2 32 ), the number of available IP addresses will soon be depleted. That is why the world will be switching over to the IPv6 system soon. 3ffe:1900:4545:0003:0200:f8ff:fe21:67cf The IPv6 addresses are 128 bits long, written in hexadecimal, and separated by colons (similar to MAC addresses, just longer) There will be 340,282,366,920,938,463,463,374,607,431,768,211,456 IPv6 addresses available (2 128 ) or approximately 340 Undecillion.

4. Private IP Addresses A private IP address is an address that is allowed to travel across an internal network, but not permitted to travel across the Internet. This allows individuals and companies to have a lot of computers internally, but only require one or more public IP address, preserving the number of available IP addresses. 10.0.0.0 - 10.255.255.255 172.16.0.0 - 172.31.255.255 192.168.0.0 - 192.168.255.255 169.254.0.0 through 169.254.255.255 ( Automatic Private IP Addressing only )

5. Identify Your Public and Private IP Address If you are using a Windows-based system, use the IPCONFIG command to display your current TCP/IP configuration details. To run the IPCONFIG command, start a Command Prompt session (click on Start, then choose [Run], then [Programs], then [Accessories] and finally [Command Prompt]). You should get a new command window. In this window, type IPCONFIG and press. If you are using a Mac-based system, the command is IFCONFIG. Click on [Go], then [Utilities] and then [Terminal]. In the Terminal window, type the command IFCONFIG.

6. Follow The OSI Model In the TCP/IP data flow, the information flows down and back up following the Open Systems Interconnection (OSI) Model. For this class, we are primarily concerned with Layers 1-4: Ethernet/Network cables and wireless signals operate at Layer 1. Switches communicate at Layer 2. Routers/Firewalls communicate at Layers 3 and 4.

7. Why Binary and Hexadecimal? Internet Follow the path.... Computer Switch Router

8. Why Binary and Hexadecimal? On the LAN, the wireless or wired Network Interface Card (NIC) on the computer is identified by the switch by Media Access Control (MAC) Address which is displayed in hexadecimal format. Computer Switch 00:10:aa:a1:2b:cce0:f8:47:aa:ba:81

9. Why Binary and Hexadecimal? On the LAN, the NIC on the switch is identified by the internal NIC on the router by the MAC Address 01:a0:cc:a4:4e:11 00:10:aa:a1:2b:cc Router Switch

10. Why Binary and Hexadecimal? Some routers, like the ones that are in the typical home, have a switch and router combined into one device.

11. Why Binary and Hexadecimal? On the WAN, the external facing NIC on the router is identified by other computers on the Internet by Internet Protocol (IP) Address, which is displayed in dotted decimal format, but actually travels across the Internet in binary format. 128.122.108.71 10000000.01111010.01101100.01000111 216.54.111.220 Internet Router

12. Why Binary and Hexadecimal? Follow the path.... e0:f8:47:aa:ba:81 10:f3:22:a1:b2:c1 192.168.1.1 128.122.108.71 32.156.253.20 192.168.1.200

13. Test You Network Connectivity You can test your connection using the PING command. PING is a command line utility that allows you to send an Internet Control Message Protocol (ICMP) request to another machine on the network which hopefully then replies. If the output indicates there is no response then there could be a problem with the network configuration or that the site is not available to receive PING requests. To run the PING program from either the Windows or Mac, simply type the ping command and an IP address or Fully Qualified Domain Name (FQDN). that The format of the PING command is: ping remote machines IP address followed by. Therefore to PING www.nba.com, whose address is 216.254.95.72, enter ping 163.1.2.1 and press or ping www.nba.com and press If everything is working correctly you should get the response similar to that shown below: PING a1570.gd.akamai.net (216.254.95.72): 56 data bytes 64 bytes from 216.254.95.72: icmp_seq=0 ttl=49 time=11.725 ms 64 bytes from 216.254.95.72: icmp_seq=1 ttl=49 time=18.069 ms 64 bytes from 216.254.95.72: icmp_seq=2 ttl=49 time=13.014 ms 64 bytes from 216.254.95.72: icmp_seq=3 ttl=49 time=14.956 ms