Chapter 1 “Introduction to Networking Concepts”

Wednesday, January 30, 2013

 In order for a computer, printer or other device with a network interface to communicate on a TCP/IP network it needs a valid network IP address.  There are five different classes used for IPv4 classful addressing.  Class A begins with the IP address 0.0.0.0 and ends with 127.255.255.255, class B begins with 128.0.0.0 and ends with 191.255.255.255, class C begins with 192.0.0.0 and ends with 223.255.255.255, class D begins with 224.0.0.0 and ends with 239.255.255.255, and finally class E begins with 240.0.0.0 and ends with 255.255.255.255. In addition, each IP address must have a subnet mask.  The subnet address for all class A addresses is 255.0.0.0, for class B address is 255.255.0.0 and for class C addresses is 255.255.255.0.  IPv4 addressing uses 32 bits (four bytes, or octets) for addressing providing the mathematical limit of 2³² possible addresses  The Internet, being as popular as it is, causes concern that the 4-billion-plus available IP address that IPv4 offers will soon be exhausted.  Because of this, IPv6, the next generation of TCP/IP protocol was developed.  IPv6 uses 128 bits, or 16 bytes, for addressing, providing 2¹²⁸ (about 340 billion) possible addresses.  IPv6 is expressed in hexadecimal notation, such as 2001:0db8:85a3:08d3:13198a2e:0370:7334, as opposed to 192.168.1.100 being an example of an IPv4 address.  Although many devices have the capability of using IPv6 it is not very popular at this time.  The Domain Name System (DNS) provides the means for associating a meaningful host name with a network address. Because of this we can use common, easy to remember names for network devices, and DNS will know what the actual IP address is.  Unless you have assigned a static IP address, meaning an address that never changes, your address will be referred to as dynamic.  Dynamic Host Configuration Protocol (DHCP) is responsible for automatically assigning IP address to the various devices on the network.  DHCP is also responsible for reassigning the IP address when the system no longer needs it.  A properly configured DHCP server will not assign the same address twice making it easier to move equipment between subnets without manually configuring them.