1. 30/11/20131.1.1 Q & A on Networking

2. Question No. 1 What is Networking? Two or more computers that are linked in order to share – Resources (such as printers & CDs) – Exchange files – Allow electronic communications 30/11/20131.1.2

3. Question No. 2 What are two basic types of Networking? Local Area Network (LAN) – Confined to relatively small geographic area Wide Area Network (WAN) – Connect larger geographic area 30/11/20131.1.3

4. Question No. 3 What are the advantages of LAN? – Speed – Cost – Security – Centralized Software Management – Resource sharing 30/11/20131.1.4

5. Question No. 4 What is a Protocol? A Protocol is a set of rules that governs the communication between computers on a network 30/11/20131.1.5

6. Question No. 5 What is Network Hardware? Network hardware includes all computers, peripherals, interface cards and other equipment needed to perform data-processing and communication within the network 30/11/20131.1.6

7. Question No. 6 What is a Switch? A Switch is a device that provides a central connection point for cables from workstations, servers, and peripherals 30/11/20131.1.7

8. Question No. 7 What is a Router? A router translates information from one network to another it is similar to a super-intelligent bridge. Routers select the best path to route a message, based on the destination address and origin. The router can direct traffic to prevent head-on collisions, and is smart enough to know when to direct traffic along back roads and shortcuts 30/11/20131.1.8

9. Question No. 8 What is Network Cabling? Cable is the medium through which information usually moves from one network device to another 30/11/20131.1.9

10. Question No. 9 What is a Topology? The physical topology of a network refers to the configuration of cables, computers, and other peripherals. Physical topology should not be confused with logical topology which is the method used to pass information between workstations 30/11/20131.1.10

11. Question No. 10 What is a Network Operating System? Unlike operating systems, such as Windows, that are designed for single users to control one computer, network operating systems (NOS) coordinate the activities of multiple computers across a network. The network operating system acts as a director to keep the network running smoothly 30/11/20131.1.11

12. IP Addressing Logical addresses are 32 bits (4 bytes) long – Each byte is represented as an octet (decimal number from 0 to 255) – Usually represented in dotted decimal notation E.g., 172.24.208.192 – Address has two parts: network and host ID E.g. 172.24.208.192 (172.24.0.0 and 208.192) – Categorized into ranges referred to as classes Class system provides basis for determining which part of address is the network and which is the host ID The first octet of an address denotes its class 30/11/20131.1.12

13. IP Addressing (cont’d) Classes – Class A: first octet between 1-126 16,777,214 hosts per network address – Class B: first octet between 128-191 65,534 hosts per network address – Class C: first octet between 192-223 254 hosts per network address – Class D: first octet between 224-239 Reserved for multicasting – Class E: first octet between 240-255 Reserved for experimental use 30/11/20131.1.13

14. IP Addressing(cont’d) The current IP addressing scheme (IPv4) defines an IP address as a 32-bit binary number 11000111 00011010 10101100 01010011 To make it more convenient for us, the IP address is divided into four 8-bit octets (bytes): 11000111.00011010.10101100.01010011 These octets are then converted from binary to decimal numbers (four decimal digits separated by periods): 199.26.172.83 When this number is entered into a computer, the machine automatically converts it to a 32-bit binary number, with no regard for the individual octets or the decimals. An IP address has two portions, a network ID and a host ID. The network ID is shared amongst all the stations on a segment and must be unique across the entire network. The host ID identifies a specific device (host) within a segment and must be unique on a particular segment. Classes When the original IP routing scheme was developed, IP addresses were divided into five classes. IP addresses most commonly come as Class A, B, or C. Class D addresses are used for multicasting, and Class E addresses are reserved for experimental and future use. Please note that in the table, N = Network and H = Host. 30/11/20131.1.14

15. IP Addressing (cont’d) ClassLeftmost Octet Start Bit Leftmost octet Last Bit Range (First octet) Network / Host PortionDefault Subnet mask A0xxxxxxx011111110 – 127N.H.H.H255.0.0.0 B10xxxxxx10111111128 – 191N.N.H.H255.255.0.0 C110xxxxx11011111192 – 223N.N.N..H255.255.255.0 D1110xxxx11101111224 – 239Not Applicable E1111xxxx11111111240 - 255Not Applicable 30/11/201315

16. IP Addressing (cont’d) 127.0.0.0 network is called the loopback address – localhost always corresponds to address 127.0.0.1 IETF reserved addresses for private networks – Class A addresses beginning with 10 – Class B addresses from 172.16 to 172.31 – Class C addresses from 192.168.0 to 192.168.255 – These addresses can’t be routed across the Internet – To access the Internet, NAT is needed – IPv6 eliminates need for private addressing; provides a 128-bit address (vs. IPv4’s 32 bits) 30/11/20131.1.16

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