ARP (Address Resolution Protocol)

It help ip network devices find other device on the same segment or Vlan |ـــــ ARP uses a local broad cast to discover neighboring device |ـــــ ARP resolves ip addresses to mac addresses so that machines on the same data link layer media can communicate with each other.


Protocol                                                                                   Protocol ID
Internet Control Message Protocol (ICMP)                                          1
Transmission Control Protocol (TCP)                                                  6
Interior Gateway Routing Protocol (IGRP)                                          9
User Datagram Protocol (UDP)                                                           17
Internet Protocol version 6 (IPv6)                                                       41
Internet-work Packet Exchange (IPX)                                                    111

What is Datagram?

A datagram is a basic transfer unit associated with a packet-switched network in which the delivery arrival time and order are not guaranteed. A datagram consists of header and data areas, where the header contains information sufficient for routing from the originating equipment to the destination without relying on prior exchanges between the equipment and the network. The source and destination addresses as well as a type field are found in the header of a datagram.

Subneting class c addresses **Normal Way!**

Before i start this article  i should say don't worry if you can't understanding it! you can see the fast way!

- In class C address, only 8 bits are available for defining the hosts.
- Remember that subnet bits start at the left & go to the right without skipping bits.
- This means that the only class C subnet mask can be following.

Binary                    Decimal                    CIDR
00000000                    0                              /24
10000000                    128                          /25
11000000                    192                          /26
11100000                    224                          /27

** We can't use /31 or /32 because we have to at least 2 host bits for assigning IP address to hosts

IP Subnet-Zero

This command allows you to use first & last subnet in your network design.
FOR EXAM:
The class C mask of 192 provides subnets 64 & 128.
BUT with the ip subnet-zero command, you now get to use subnets 0 , 64, 128 & 192.
* that is two more subnets for every subnet mask use.

Subneting a class C address *** THE FAST WAY! ***

You need to do is answer five simple questions:

1. How many subnets does the chosen subnet mask produce?
2. How many valid hosts per subnet are available?
3. What are the valid subnets?
4. what's the broad cast address of each subnet?
5. what are the valid hosts in each subnet?

well ...

Types of IP addresses

Types of addresses are:   1-Unicast  2-Multicast  3-Broadcast   

                   First Network ID            Last Network ID

Class A            1.0.0.0                          126.0.0.0

Class B          128.0.0.0                      191.255.0.0             127.0.0.1 is Loop Back

Class C          192.0.0.0                     223.255.255.0