Sunday, September 13, 2015

How to Build a Gaming Computer: DIY Gaming PC Step-By-Step Tutorial


In this video you will learn how to build a pc step by step.

Windows 10 - Beginners Guide [Tutorial]


How to Create a Portable Virtual Windows 7


Subnetting



The sub netting procedure divides a network into several sub networks in such a way that each of these subnets has its own address. The subnet address is created by dividing the host address into network address.
There are five steps in subnetting:-
1.  Requirement Analysis
2.  Partitioning network address and host address
3.  Determining the subnetting mask
4.  Determining subnet address
5.  Determining the host address for each subnet
For e.g.  IP address is 211.71.9.0
And subnets that have to create are 8 subnets by following the five steps:
1       Requirement analysis: In this step which class has to do subnetting and how many subnets will be there? The class A and class B avoid creating subnetting because there are many host computers, and class C has the minimum number of hosts. Subnets are always created in the power of 2. Therefore 2*2*2=8 subnets
Convert the address into binary format i.e. 11011011.01000111.00001001.00000000
2    Partitioning network address and host address: - 000.00000:- In this first three bits are assigned for subnet bits and last five bits are assigned for host bits. So, 2*2*2*2*2-2=30 host computers.
3     Determining the subnet mask
      000 0000
      111 0000 -224
Convert the subnet bits into 1’s:
255.255.255.0
255.255.255.224
4 Determine the address of subnet
   211.71.9.0
   000:00000-0
   001:00000-32
   010:00000-64
   011:00000-96
   100:00000-128
    101:00000-160
     110:00000-192
     111:00000-224
Subnet Address:
211.71.9.0
211.71.9.32
211.71.9.64
211.71.9.96
211.71.9.128
211.71.9.160
211.71.9.192
211.71.9.224
5 Determining the host address:-
211.71.9.0
000 0000 
000 11110-30
              211.71.9.32
              001 00001
     
             001 11110-62
            211.71.9.64
            010 00001
    
           010 11110-94
           211.71.9.96
            011 00001
      
           011 11110-126
           211.71.9.128
           100 00001
     
           100 11110-158
           211.71.9.160
            101 00001
     
         101 11110-190
           211.71.9.192
           110 00001
     
          110 11110-222
          211.71.9.224
         111 00001
    
        111 11110-255

Supernetting



Most of the class A and class B address were depleted how ever there was still a huge demand for mid size blocks. In this super netting decrease the number of ones in the mask. But the main disadvantages of super netting is, there is wastage of host computers, so to overcome use CIDR (classless inter domain outing) notation. To overcome address depletion to give more organization access to the internet, classless addressing was designed and implemented. Here are no classes, but the addresses are still granted in blocks.

TCP SEGMENT



TCP segment is the unit of data transfer between any two devices that use TCP. The segment is divided into two parts. The part is called as header part and other one is called is data part.
TCP header format:                    
       
1)  Source Port Address: - It defines the application program in the source computer and is 16 bit wide.
2)  Destination Port Address: - The destination port address defines the application program in the destination computer. It is also 16 bit wide.
3)  Sequence Number: - A stream of data from the application program may be divided into two or more TCP segment.
4)  Acknowledgement number: - The 32 bit acknowledgement number is used acknowledge the receipt of data from the other communicating device.
5)  Header Length: - The 4- bit header length field indicates the number of 32 bit (4 byte) words in the TCP header.
6)  Unused: - The 6 bit field is reserved for future use.
7)  Control: - Each bit of the 6 bit control field functions individually and independently. A bit can either define the use of a segment.
Control Field:
URG
ACK
PSH
RST
SYN
FIN

                             i.            URG: - Urgent pointer is valid.
                          ii.            ACK:-Acknowledgement is valid.
                      iii.            PSH: - Push the data.
                        iv.            RST:-Reset the connection.
                           v.            SYN:-Synchronize sequence numbers during the connection FIN.
                        vi.            FIN:-Terminate the connection.
8)  Window size: - The field defines the size of the window in bytes. The length of this field is 16 bits, which means the maximum size of the window is 65,535 bytes.
9)  Checksum: - The 16 bit contains the checksum. It is generally used in error detection.
10)   Urgent pointer: - The 16 bit field, which is valid only if the urgent flag is set. In this the pointer defines the end of the urgent data and the start of the normal data.
11)   Options:-There can be up to 40 bytes of optional information in the TCP header. They are used to conventional additional information to the receiver or for alignment purpose.