3 Types of IP Addresses: Network Address, Host Address, and Broadcast Address

Network Address - The address by which we refer to the network
      Uses the first address in the network,
      The network address is reserved and is not usable by a host
      All hosts in a network will have the same network address
      All hosts in a network will have the same network bits or network portion

Broadcast Address - The address used to send data to all of the hosts on a network
      Uses the highest (last) address in the network,
      The broadcast address is reserved and is not usable by a host
      The bits in host portion are all 1's
      Also called a directed broadcast

Host Address - The addresses assigned to the end devices in the network
      Each and every device in the network needs a unique ip address,
      The host addresses lie between the network and broadcast address

Public and Private Addressing

Private addresses are blocks of ip addresses that are not routable on the internet. The private address blocks are:

10.0.0.0 to 10.255.255.255   (10.0.0.0 /8)
172.16.0.0 to 172.31.255.255   (172.16.0.0 /12)
192.168.0.0 to 192.168.255.255   (192.168.0.0 /16)

Since private addresses are implemented on LANs behind a firewall different networks may use the same private address schemes. Private addressing requires Network Address Translation (NAT) in order to translate private addresses to public addresses for use on the internet. With this (NAT) technique, many hosts in a private network can channel all communications through a single public ip address allowing communicate over the internet.

Public Addresses are designed to be used by hosts that are publicly accessible from the internet. Public ip addresses are assigned by the InterNIC and consist of class-based network IDs called CIDR blocks.

Video Tutorial Series - IP Addresses, Binary Conversion, and Network Masks

In order to understanding of subnetting you need to be able to convert ip addresses to binary. In fact subnetting, and by this I mean networks, subnetworks, and masks only make sense from the perspective of binary. The reason you need to convert to binary is that it is the way routers find networks. Routers and computers find networks by ANDing ip addresses with the subnet masks. If you want to understand the logic behind the process you need to be able to see it from the perspective of the router. In the following video tutorials I lay out the simple process of converting ip addresses and subnet masks to binary. I also cover finding the network portion and host portion of a network or subnetwork mask. I recommend watching all of these videos as as my following series on the "Magic Number."

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Title: Subnetting, Cisco CCNA, Binary Numbers -Part 1 (0:06:57)

Video Tutorial Series - Subnetting with the Magic Number

In this series of tutorials I explain how you can easily find the network address, broadcast address, and first and last host addresses from any ip address and subnet mask combination. The ability to calculate subnets is the most important skill for success in the Cisco CCNA. The magic number trick will make that process a snap!

Unicast, Broadcast, and Multicast Messaging 

A message or packet sent to a unique ip host address is called a unicast message. A unicast message is a message addressed to a single unique host. By contrast a message or packet sent to a broadcast address is called a broadcast message. It is a message meant for all hosts on a network. A multicast message is a message sent to a multicast address, typically an address starting with 224 like 224.0.0.1. An address that starts with 224 is a Class D address which is an address space reserved for multicasts. A multicast message is like a broadcast message in that most, or all, hosts on the network will open the packet and examine its contents before deciding whether or not to drop the message or send it up the layers for decapsulation.