IP Addressing Principles

IP Addressing Principles

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  IP Address Classes ClassA 1 – 127 (Network 127 is reserved for loopback and internal testing) Leading bit pattern 0 00000000.00000000.00000000.00000000 Network . Host . Host . Host Class B 128 – 191 Leading bit pattern 10 10000000.00000000.00000000.00000000 Network . Network . Host . Host Class C 192 – 223 Leading bit pattern 110 11000000.00000000.00000000.00000000 Network . Network . Network . Host Class D 224 – 239 (Reserved for multicast) Class E 240 – 255 (Reserved for experimental, used for research) Private Address Space Class A 10.0.0.0 to 10.255.255.255 Class B 172.16.0.0 to 172.31.255.255 Class C 192.168.0.0 to 192.168.255.255 Default Subnet Masks Class A 255.0.0.0 Class B 255.255.0.0 Class C 255.255.255.0 Produced by: Robb Jones [email protected] Frederick County Career & Technology Center Cisco Networking Academy Frederick County Public Schools Frederick, Maryland, USA Special Thanks to Melvin Baker and Jim Dorsch for taking the time to check this workbook for errors, and to everyone who has sent in suggestions to improve the series. Workbooks included in the series: IP Addressing and Subnetting Workbooks ACLs - Access Lists Workbooks VLSM Variable-Length Subnet Mask IWorkbooks Inside Cover
• 2.
  ANDING With Default subnet masks Every IP address must be accompanied by a subnet mask. By now you should be able to look at an IP address and tell what class it is. Unfortunately your computer doesn’t think that way. For your computer to determine the network and subnet portion of an IP address it must “AND” the IP address with the subnet mask. Default Subnet Masks: Class A 255.0.0.0 Class B 255.255.0.0 Class C 255.255.255.0 ANDING Equations: 1 AND 1 = 1 1 AND 0 = 0 0 AND 1 = 0 0 AND 0 = 0 Sample: What you see... IP Address: 192 . 100 . 10 . 33 What you can figure out in your head... Address Class: C Network Portion: 192 . 100 . 10 . 33 Host Portion: 192 . 100 . 10 . 33 In order for you computer to get the same information it must AND the IP address with the subnet mask in binary. Network Host IP Address: 1 1 0 0 0 0 0 0 . 0 1 1 0 0 1 0 0 . 0 0 0 0 1 0 1 0 . 0 0 1 0 0 0 0 1 (192 . 100 . 10 . 33) Default Subnet Mask: 1 1 1 1 1 1 1 1 . 0 1 1 1 1 1 1 1 . 1 1 1 1 1 1 1 1 . 0 0 0 0 0 0 0 0 (255 . 255 . 255 . 0) AND: 1 1 0 0 0 0 0 0 . 0 1 1 0 0 1 0 0 . 0 0 0 0 1 0 1 0 . 0 0 0 0 0 0 0 0 (192 . 100 . 10 . 0) ANDING with the default subnet mask allows your computer to figure out the network portion of the address. 8