Subnetting Class C Network in a Nut Shell

Here is the exercise I have promised to my students. This is a fun part subletting and this question is very basic or I would say simple. The idea is to learn or understand the basic behind this question. Why do we need subletting seem to be a command question for many of my students, the answer is , would you b e more comfortable if you have to go to work and sit within the room with 50 people? Or would you prefer sitting in a office by yourself if you have to go to work every day. Obvious, answer will be, you want to sit by yourself in a dedicated office for many reasons. The reasons follow as

1. Security ( you don't want others figured out what web sites you are browsing on the internet , and trying to blog about exchange 2007 or Active Directory, or participating MSExchange.org forums, while you are on your company payroll (-J )
   
2. Less or none destructions by others, since you don't see and won't hear from them, when you shut your office door. This will give you a speed and you will be able to answer a lot of question posted on MSExchang.org
   
3. Since you have dedicated office if at the end of the year, MSExchange.org sends you a nice XMAS basket, less change a jealous colic would steal your beautiful XMAS basket. I mean you are easy to be located by others because your office has a number called (MAC address) on it.
   

Please answer the following questions

1. What is the full subnet mask?
   
2. How many Networks
   
3. How many hosts in each network
   
4. What is the IP Address of the each network?
   
5. What is the Default gateway of each network?
   
6. What is the Broadcast IP for each network?
   
7. What is the Broadcast IP for each network?
   
8. What is the IP address of PC2 and PC3?
   
9. What is the Subnet mask for PC2 and PC3?
   
10. What is the DGW IP for PC2 and PC3?
    
11. What is the IP address of PC4 and PC5
    
12. What is the Subnet mask for PC4 and PC5?
    
13. What is the DGW IP for PC4 and PC5?
    

    
    

As you see from above examples there are many advantages subletting. Don't forget IP Address is 32 Bits Binary number. Subnet mask is 32 bits binary number as well. The primary function of IP address is to provide communication in TCP/IP world we live in. The primary function of SM (Subnet mask) is to divide 32 bit complicated binary number IP Address into two distinct parts,

• Network
  
• Host
  

If two hosts belong to same network they can talk happily each other without needing to go through a router. However if two hosts are in two different network they must go through a router in order to talk. At least this is the basic to understand the purpose of Subnetting

The IP address of 0.0.0.0 is used for the default network.

What is an IP address?
IP address is a network layer protocol address for a host in a TCP/IP network. Or IP Address is 32 is 32 Bits binary number.

What are the components of an IP address?

An IP address consists of the following components:

• Network ID
  
• Host ID
  

For Instance, IP address 10.10.10.100 \24 subnet mask would produce as following results

• Network ID 10.10.10
  
• Host ID 100
  

What is a network ID?

A network ID uniquely identifies a network. All the hosts in a single network will have the same network ID. For example, in the IP address, the network ID is 10.10.10 A router analyses only the network ID portion of an IP address for datagram forwarding.

What is a host ID?

A host ID uniquely identifies a host in a network. Two hosts in two different networks can have the same host ID.

Example, in the IP address 10.10.10.100 host ID 100

What is a broadcast IP address?

The datagram with a broadcast IP address is received and processed by all the hosts in the local network. For example, the IP addresses 255.255.255.255, 10.10.10.255, 10.10.255.255, 10.255.255.255 are broadcast IP addresses.

What are the different classes of IP addresses?

• Class A
  
• Class B
  
• Class C
  
• Class D
  
• Class E
  

IP Address Class	Maximum number Networks	Max Num Hosts In each Network
Class A	126 (2^7 - 2)	16.777.214 (2^24 - 2)
Class B	16.384 (2^14)	65.534 (2^16 - 2)
Class C	20.971.52 (2^21)	254 (2^8 - 2)
Class D	-	-
Class E	-	-

What kind of networks use a Class A or Class B or Class C IP address typically?
Class A IP address is used for a network with large number of hosts. Class C IP address is used for a network with less number of hosts. Class B IP address is used for a network with medium number of hosts

What is the use of Class D IP addresses?
The Class D IP addresses are used for multicasting.

What is the use of Class E IP addresses?
The Class E IP addresses are reserved for experimental purpose

Oz ozugurlu,
Systems Engineer
MCITP (EMA), MCITP (SA),
MCSE 2003 M+ S+ MCDST
Security Project+ Server+
oz@SMTp25.org
http://smtp25.blogspot.com