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How to find the Subnet Mask in Computer Networks

How to find the Subnet Mask ?

Subnet Mask is a 32 bit binary number.The subnet mask contains all 1's in the network and subnet portion of the address and all zeros in the host potion of the address.

Example.

200.129.41.0  is a Class C address . We need to create 14 subnet on this network. Find the Subnet Mask?

The default mask for this address is 255.255.255.0.To perform subnetting we need to borrow bits from the host part. So we represent the host part of 200.129.41.0 in binary form.

200.129.41.00000000

If we borrow 4 bits from the host part can create 14 subnets.

That is 2n - 2  = 24 - 2 = 16 - 2 = 14

So from the host part of 200.129.41.00000000 we borrow 4 bits.

200.129.41          |   0000          |     0000 
Network Address    Subnet Bits     Host bits

 

The 32 bit Subnet Mask is given by all 1's  in the network and subnetwork portion and all 0's in the host portion.

11111111.11111111.11111111.11110000

255          .255         .255         .240

 

So the subnet mask is given by 255.255.255.240

 


         

Difference Between TCP and UDP in Computer Networks

Difference Between TCP and UDP

TCP : Transmission Control Protocol
  • Connection Oriented
  • Reliable
  • Slow
  • Overhead is high
  • Byte Oriented
  • Using in Critical Applications like FTP
  • TCP is a Concurrent protocol
TCP follows connection oriented communication. Also the communication using TCP is reliable as it ensure the delivery of packets. TCP generally uses cumulative acknowledgment to inform the sender that all the packets are received. Undelivered packets or packets with error are re-transmitted.

UDP : User Datagram Protocol
  • Connection less
  • Not Reliable
  • Fast
  • Overhead is low
  • Message Oriented
  • Using in real time applications and multimedia
  • UDP is an iterative protocol
 
UDP is a connectionless protocol.UDP does not ensure the delivery of packets, so it is not reliable.It does not uses acknowledgment.And is mainly used in  real time applications and multimedia where the importance is for the latest data.There is no provision for re-transmission of packets.
 
 

IP Version 6 in Computer Neworks

IP Version 6  in Computer Neworks

IP Version 6

The newer IPv6 is a 128 bit addressing system. The new address space thus supports 2 power 128 addresses.
The IPv6 addresses are represented by eight groups of four hexadecimal digits, where each group is separated by a colon (:).

6002:0dc8:85b3:0000:0000:8c2d:0480:8445 is an example for IPv6 address.
 

IP Address in Computer Networks

What is IP Address in Computer Networks?

IP Address is the logical address assigned to a device on a network for identification purpose. The IP address uniquely identifies computers on a TCP/IP network.

  • IP version 4
  • Private IP Address
  • Public IP Address
  • Static IP Address
  • Dynamic IP Address
  • IP version 6
Two different IP addressing standards are in use today namely IPv4 and IPv6.The IPv4 standard is most popular and supported everywhere.The  IPv6 standard is considered as a replacement for the present IPv4 and will be to be deployed in the near future.
 
IP Version 4 

IP version 4  is a 32 bit addressing system. The 32 bits are divided as 4 octets of 8 bits each.In IPv4 the ip address is categorized as Class  A, Class B, Class C, Class D,Class E.

Example
10.20.20.33 - Class A
191.122.33.22 – Class B
192.168.20.1 – Class C
 
Private IP Address vs Public IP Address

Private IP address is for use on a local area network (LAN) . Public IP address is for use on a public network like internet.
 
Static IP Address vs Dynamic IP Address

In static IP address assigning the IP address is assigned by a system administrator.The IP address is asssigned dynamically  by another device on the network on demand.
 
IP Version 6

The newer IPv6 is a 128 bit addressing system. The new address space thus supports 2 power 128 addresses. The IPv6 addresses are represented by eight groups of four hexadecimal digits, where each group is separated by a colon (:).
6002:0dc8:85b3:0000:0000:8c2d:0480:8445 is an example for IPv6 address.
 
 
 

Physical layer in ISO OSI Model

 

Functions of Physical layer in ISO OSI Model


 Physical layer deals with electrical , mechanical , functional and procedural characteristics interface and media.

  1. Representation of bits.

  2. Synchronization of bits.

  3. Topological specification.

            physical layer is responsible for selecting the appropriate topology. ( bus, ring,mesh, star,tree )


  4. Type of link.

            Point to Point.
            Broadcast.

  5. Define transmission mode.

           Simplex : Here data can be transmitted only in one direction.
                         eg. keyboard, CPU to monitor.

            Half Duplex : Here data can be transmitted in both directions but not simultaneously.
                          eg. Walkytalky.

            Full Duplex :Here data can be transmitted in both directions simultaneously.
                           eg. telephone cable. computer cable.