Thursday, 28 January 2021

Network Address Translation (NAT)

What is NAT?

NAT stands for “Network Address Translation” it allows a host that does not have a valid registered IP address communicates with other hosts through the internet. NAT uses a valid registered IP address to represent the non-registered IP address. Non-registered IP address used inside a network that is known as “Private Address”. NAT operates on a router, usually connecting two networks together, and translates the non-register private addresses into registered legal public addresses before packets are forward to another network. NAT offers the dual functions of security and address conservation and is typically implemented in remote-access environments. It allows a single device, such as a router, to act as an agent between the public network or internet and private network or local network and a single unique IP address is required to represent an entire group of computers to anything outside their network.

NAT Addresses Types

Inside Addresses - It refers to the addresses which must be translated.

Outside Addresses - It refers to the addresses which are not in control of an organization.

Example for NAT

Inside Local Address

Inside the local network assigned an IP address to the host is known as Inside local address. These IP addresses are the private IP address and these inside hosts can be accessed from the inside network.

Inside Global Address

One or more inside local IP address represents to the outside world is known as inside global address. These inside hosts can able to access from the outside network.

Outside Local Address

After translation, the outside local address is the actual IP address of the destination host in the local network.

Outside Global Address

Before translation, the outside global address is the IP address of the outside destination host, where, the outside host can able access from the outside network.

Range of IP Address

1. Class A – 10.X.X.X ( TO

2. Class B – 172.16.X.X ( to

3. Class C - 192.168.X.X ( to

NAT Types

There are three types of NAT Configuration

  1. Static NAT
  2. Dynamic NAT
  3. Overloading NAT

Static NAT

A single private IP address is map with a single public address that is one to one mapping between the local and global addresses. This technique is generally use for web hosting. In this, users can also able to configure static address translation at a port level, and also use a remainder for other translations. This can be possible only if you were performing Port Address Translation (PAT). For example, if there are 1000 network devices are available which need access to the internet, then the organization needs to buy 1000 public IP addresses that will be very costly to buy.

Dynamic NAT

A private IP address is translate into a public IP address from the pool of IP address or interface IP address that is the users can establish dynamic mapping between the local and global addresses. Such that sets up a pool of possible inside global addresses and defines criteria for the set of inside local IP addresses whose traffic should be translated with NAT. For example, if there is a pool of 2 public IP addresses then only 2 private IP addresses can be translated at a given time. If 3rd private IP address wants to access the Internet then the packet will be dropped because of this the organization has to buy many global IP addresses to make a pool is also very costly to buy.

Overloading NAT with PAT

NAT overload uses PAT (Port Address Translation) this is a translation table entry containing the IP address and source/destination port information, which is called PAT or overloading. In this, many private IP addresses can be translate into a single public IP address and port numbers are use to identify the traffic (i.e. which traffic belongs to which address). It supports lots of inside local IP addresses with only a few inside global or publicly registered IP addresses. Instead of just translating the IP address, it also translates the port number.

Benefits of NAT

  • Conserves legally registered IP addresses
  • Eliminates address renumbering when a network evolves.
  • Provides privacy as the device IP address
  • Sending and receiving the traffic, will be hidden.

Drawbacks of NAT

  • Delays translation results in switching path
  • when NAT is enable certain applications will not function
  • Complicates tunneling protocols such as IPsec.

Application Layer Gateway (ALG)

ALG is an Application Layer Gateway (ALG). NAT performs translation service on any Transmission Control Protocol/User Datagram Protocol (TCP/UDP) traffic that does not carry source and/or destination IP addresses in the application data stream. These protocols include FTP, HTTP, SKINNY, H232, DNS, RAS, SIP, TFTP, telnet, Archie, finger, NTP, NFS, rlogin, rsh, rcp. Specific protocols that embed IP address information within the payload require the support of an Application Level Gateway (ALG).

NAT Software List

  • Internet Connection Sharing (ICS) – NAT & DHCP implementation for Windows desktop operating systems
  • IPFirewall (IPFW) - FreeBSD Native Packet Filter
  • IPFilter includes Solaris (Open) and NetBSD for Unix operating systems
  • Routing and Remote Access Service – Routing implementation for Windows server operating systems
  • WinGate – Third party implementation for Windows operating systems
  • NetFilter with IPTables and NFTables – Linux Packet Filter
  • Native Packet Filter (NPF) – NetBSD
  • Packet Filter (PF) – OpenBSD

Also learn about Integrated Services Digital Network (ISDN)


Net Send

What is Net Send?

Net Send is a command that used to sends messages to other computers, PC users, or messaging names on the computer network. The Messenger service should be running to receive netsend messages. In this user can send a message only to a name that is online on the network. If the message is sent to a specified username, that user must be logged on and running the Messenger service to receive the netsend message.

How to use Net Send Command

First Click on “Start” button -> Choose “Run” -> type “cmd” then click enter button-> command prompt (cmd.exe) will appear -> type Net Send command syntax as “NET SEND {name | * | /Domain[:name] | /USERS} message”

Where, the followings are

  • Name -> Can be user name, PC name, or messaging name to send the message to. If the name is a computer name that contains blank characters, it need to be enclosed the alias in quotation marks (" ").
  • * ->Sends the message to all the names in your group.
  • /DOMAIN[:name] ->Sends the message to all the names in the workstation domain. If name is specified, the message is sent to all the names in the specified domain or workgroup.
  • /USERS - >Sends the message to all users connected to the server.
  • Message ->Is text to be sent as a message.

Examples for Net Send Command

  • For send a message to another user: NET SEND anna_81 See you soon, bye.
  • To send a LAN message to another machine: NET SEND PCW231 Let's go have a dinner.
  • For send a broadcast message to the whole domain: NET SEND * This server will shut down in 5 minutes.
  • To send a message to all users who have a session with the server: NET SEND /USERS Shutdown all computers, please.

Also learn about InfiniBand


Minimum Requirements for Networking

Minimum Requirements for Networking

The minimum requirements for networking are 4 to 6 computers and 4 to 6 network interface cards, Cat 6 cables for LAN connections and 4 to 6 network operating systems software, 4 to 6 IP addresses for network connections, and the set of rules (network protocol). The minimum requirements for networking are 4 to 6 computers and 4 to 6 network interface cards, Cat 6 cables for LAN connections and 4 to 6 network operating systems software, 4 to 6 IP addresses for network connections, and the set of rules (network protocol).

The following Minimum Requirements For Networking is

  1. PC’s
  2. NIC ( N/W interface card  (or) Either net card )
  3. Cables  & Connector
  4. Network OS
  5. IP-Address (Internet protocol)
  6. Protocol (Set of  rules)

PC’s (Computers)

Therefore networking we need to buy 4 to 6 computer sets like Monitors, Cabinets with CPU, Keyboards, and Mouse. Such as the basic essentials for computer systems to work fine. However, a CPU is a central processing unit it contains Motherboard, RAM, Processor, FAN, SMPS, CMOS battery, and VRAM.

NIC (N/W interface card  (or) Either net card)

A Network Interface Card (NIC) is used to connect computers to the network with the help of LAN cable (CAT 6). Therefore it provides connection between the computers and connects to the internet. It is also know as Ethernet Adaptor, LAN Adaptor, and Network Adaptor.

Cables  & Connector

A cables and connector is used to connect computers to communicate each other. Therefore LAN cables (CAT 5 or CAT 6 cables) are connect with ethernet cards to share information with each computer.

Network OS

An Operating system is software that interfaces between computer hardware and computer users. Therefore in network operating systems, it has features like DNS configuration, Active Directory configurations, SQL management, etc,.

IP-Address (Internet Protocol)

Protocol (Set of  rules)

Also Learn about Mesh Topology


Mesh Topology

What is Mesh Topology?

Mesh Topology is a topology in which each computer has alternative ways to communicate with each other. It provides both advantages and disadvantages. It is a local area network that includes switches/hubs, bridges, cables, and nodes to directly connect. A mesh net is a self-organized and self-configured network. The dynamic distribution of workloads is enabled by a self-configured network.

It is maybe contacted to star or tree network therefore where bridges and switches are directly linked to a small subset of other bridges and switches and the link between this hierarchical. Where star and tree networks are highly standards, vendor assure and well establish, but mesh network devices are not all agreed for its standards and also because the ability of computers to exchange between different devices from a different vendors is not assure. Therefore in mesh network it transfers data from node to node by checking his path is available or broken. If the path is broken then it reconfigure itself by using the shortest path bridging algorithm then move forward.


  •  The Reliability is high.
  •  It is a Centralized and secured Administration.


  •  The required more Number of Cables.
  •  Its configuration is Complicate.

Also Learn about Hybrid Topology


Wednesday, 27 January 2021

Managing Disk

What is Managing Disk?

The Managing Disk is was use to manage the partition to increase the performance and provide a flawless usage to the user and it was divide into two types one is basic and another one is Dynamic Disk.

Types of Disks

  1. Basic Disks
  2. Dynamic Disks

Difference Between Basic and Dynamic Disks

S No.




Created By Default

         To Be Converted Form Basic Disk


Partition Can Be Created

         Volume Con Be Created


Two Type Of Partitions Available

         Five Type Of Volume Available


A Minimum Of 4 Partition Can Be Created

         Unlimited Number Of Volume Can Be                                Created

Note: Two Partitions Are

1) Primary     

2) Extended

Each Primary Partition Can Have Extended Partition

*Extended Can Be Farther Divide In To Logical Driver

Advantages of Managing Disk

  1. Increased Read/write Performance
  2. Gives Fault Tolerance (Or) Data Redundancy (Eliminating With Out Loss)

Basic Disks

A basic disk is a common type of partitions and logical drives use in Windows operating systems to manage all the partitions and data on the hard disk. The basic disk uses partition tables and logical drives. It contains primary partitions and an extended partitions with multiple logical drives.

Dynamic Disks

Dynamic disk is a dynamic volume which has the following types of volumes such as simple volume, striped volume, spanned volume, Mirror volume, and stipe with parity.

Also Learn About Types Of Volumes : [Dynamic Disks]


Local Area Network (LAN)

What is LAN?

LAN stands for “Local Area Network” is a network that is contains within a limited area, such as a single building (school, residence, laboratory, college, university campus, office). Every computer connected to the network (via LAN) is said to be “on the network”. The technical term for a computer that’s on the network is a node. Local Area Network has the two most common technologies such that Ethernet and Wi-Fi.

Types of LAN

There are two types of LAN such that client/server LAN and peer-to-peer LAN. A client/server LAN consists of several devices (the clients) connected to a central server. The server manages file storage, application access, device access, and network traffic. A peer-to-peer LAN doesn't have a central server and cannot handle heavy workloads like a client/server LAN can, and so they're typically smaller. On a peer-to-peer LAN, each device shares equally in the functioning of the network. The devices share resources and data through wired or wireless connections to a switch or router. Most home networks are peer-to-peer.

What is Ethernet?

Ethernet is the most common type of computer network used in local area network (LAN), a wide area network (WAN), and a metropolitan area network (MAN). Therefore the Ethernet has a standard packet format that all packets sent on an Ethernet network must follow. An Ethernet packet contains the following information.

Ethernet Packet Information

  • Preamble: The preamble consists of 56 bits of alternating ones and zeros and is use to synchronize the precise timing required to read packet data.
  • Start-of-frame marker: A start-of-frame marker is a single byte that indicates that the frame is about to begin.
  • Destination MAC address (six bytes).
  • Sender MAC address (six bytes).
  • Tag: The tag, which is use to support virtual local area networks (VLANs), is optional. Therefore a VLAN lets you divide two or more distinct LANs on a shared physical infrastructure.
  • Ethertype (two bytes): This field indicates the specific protocol that is contains in the payload.
  • Payload: The payload contains the actual data being sent by the packet. The payload can be anywhere from 46 to 1,500 bytes. If the information that needs to be sent is longer than 1,500 bytes, the information must be broken into two or more packets, sent separately, and then reassembled when the packets reach their destination. Therefore the tasks of breaking up and reassembling the data are handle by protocols at higher layers in the OSI framework. Ethernet itself has no understanding of what is in the packets it sends.
  • Frame check sequence (four bytes): The frame check sequence (FCS) is used to ensure that the frame data was sent correctly. Basically, the interface that sends the packet uses an algorithm to calculate a four-byte number based on the contents of the frame and saves this number in the FCS field. When the packet is receive, the receiving interface repeats the calculation, and then makes sure that the number recorded in the FCS portion of the packet matches the number it calculated. If the numbers disagree, the packet got garble in transmission and is discards.

What is Wi-Fi?

A Wi-Fi is stands for “Wireless Fidelity” is a common name for wireless networking technology. Wi-Fi Access Point that works with most 802.11 Wi-Fi standards and protocols, including 802.11ac. They are commonly used for local area network of devices and Internet access.

Also learn about IP Routing


Layers of ISO Model

Layers of ISO Model

OSI layers it is a layered architecture, which defined the network standard given by the ISO and therefore OSI layers has standardized level of service & type of interaction for computer exchanging information through a communication network.

ISO: International Standard Organisation

IOS : International Organisation for Standardization

OSI: Open System Interconnects

However, the OSI models separates computer to computer communication into several protocol layer ‘s and the highest one is application layer & the lowest is Physical layer.


  1. It divides the N/W communication process into smaller and simpler components, thus easy to design, develop & trouble shoot.
  2. It allows multiple vendors development through standards and therefore it allows different manufactures hardware & N/W components to communicate.
  3. Therefore it prevents changes in one layer, affecting the other layer.

ISO Layers

  3. SESSION                  LAYER
  4. TRANSPORT            LAYER
  5. NETWORK              LAYER
  6. DATA LINK            LAYER
  7. PHYSICAL              LAYER

NOTE: Different Protocol used in all layers

1) Application Layer

The application layer is the 7th layer and it serves as an abstraction layer that specifies the shared communications protocols and interface methods used by hosts in a communications network and the application layer abstraction is used in both of the standard models of computer networking and the OSI model and this layer is responsible for file, folder, printing ,messaging data and other application services.

2) Presentation Layer

The presentation layer is the 6th layer and serves as the data translator for the network and It is also called the syntax layer and this layer is responsible for data translating and code formatting and therefore it provides coding & conversion function and the tasks like data compression, decompression , encryption , decryption , or associated with this layer and the code conversion are EBCDIC (EXTENDED BINARY CODE DECIMAL INTENDED CODE) and ASCII (AMERICAN STANDARD CODE FOR INFORMATION INTERCHANGE).

3) Session Layer

The Session Layer is the 5th layer and it provides the mechanism for opening, closing and managing a session between end-user application processes and this layer is responsible for setting up (or) start , managing & terminating the session therefore it co-ordinate communication between system and server to organize their communication.

4) Transport layer

The Transport layer is 4th layer and this layer is responsible for segmenting and unites them on to the data stream and therefore it provide end to end data services and can establish logical connection between the sending host & destination host and they provide reliable or unreliable delivery performs error correction before transmitting (It divides the segment).

5) Network Layer

The Network Layer is a 3rd layer and this layer is responsible for managing N/W devices (Router) and therefore it tracks the location of devices and determines the best path to develop the routing information table and the two types of packets are used they are Data and Root Update.

6) Data Link Layer

The Data Link Layer is the 2nd layer and this layer is the protocol layer that transfers data between nodes on a network segment across the physical layer and this layer is responsible for coding, addressing, transmitting information and framing and therefore it formats the massage into pieces called as a data frames and such as Switches & Bridges work in this layer.

7) Physical Layer

The Physical Layer is the 1st layer and this layer is responsible for sending & receiving the bits (0,1) and therefore it specifies electrical mechanical & functional requirements for activating maintaining physical links between systems and it interfaces DTE & DCE for communication and such as Modem, Hub, Repeater works in this layer.

Also Learn About OSI Layers Protocols



What is ISP?

ISP stands for "Internet Service Provider". It is an organisation that provides services for participating, accessing, or using in the Internet. Such that the Internet service providers are organised in different forms. The forms are community owned forms, private owned forms, commercial forms, or non-profitable forms. ISP's can be used to provide Internet Services that may be include Colocation, Internet access, Web hosting, Internet transit, Usenet service, and Domain name registration. An ISP is actually act as access point or the gateway to the user, which provides access to everything available on the Internet to the user.

History of ISP

In 1980's Online Service Provider were establish as CompuServe and America On-Line (AOL) and process set in place towards public. Began to offer limited capabilities to access the Internet, such as E-mail interchanging. But full access to the Internet was not readily available to the general public.

The first Internet Service Providers was introduced in 1989 and established in Australia, therefore the companies offers a direct access to the Internet, was readily available to the general public for a monthly fee. They are generally a dial-up connections which offered by a companies, they provide the Internet connections to their customer by using a public telephone network.

Already a cable television company and the telephone carriers are had a wired connections which provide a high speed Internet connections than dial-up to the customer by using broadband technology such as digital subscriber line (DSL) and cable modems.

Classifications of ISP

  • Access Providers – Provide Internet Access
  • Mailbox Providers – Provides Hosting Electronic Mail Domain Services
  • Hosting ISP's – Provides Email, Web Hosting or Online Storage Services
  • Transit ISP's - Just as their customers pay them for Internet access, ISP's themselves pay upstream ISP's for Internet access
  • Virtual ISP's (VISP) – It is an operation that purchases services from another ISP
  • Free ISP's – It is Internet service providers that provide service free of charge
  • Wireless ISP's – It is an Internet service provider with a network based on wireless networking.

Also learn about LAN (Local Area Network)


ISO Network Management Model

ISO Network Management Model

The ISO Network Management Model has contributed a great deal to network standardization. Its network management model is the primary means for understanding the major functions of network management systems. This model consists of five conceptual areas.

1. Performance Management

The goal of performance management is to measure and make available various aspects of network performance so that internet work performance can be maintain at an acceptable level because of performance variables that might be provided include network throughput, user response times, and line utilization.

2. Configuration Management

The goal of configuration management is to monitor network and system configuration information so that the effects on network operation of various versions of hardware and software elements can be tracked and managed.

3. Accounting Management

The goal of accounting management is to measure network utilization parameters so that individual or group uses on the network can be regulated appropriately, such regulation minimizes network problems (because network resources can be apportioned based on resource capacities) and maximizes the fairness of network access across all users.

4. Fault Management

The goal of fault management is to detect, log, notify users of, and (to the extent possible) automatically fix network problems to keep the network running effectively, therefore, fault management is perhaps the most widely implemented of the ISO network management elements and the faults can cause downtime or unacceptable network degradation.

5. Security Management

The goal of security management is to control access to network resources according to local guidelines so that the network cannot be sabotaged (intentionally or unintentionally) and sensitive information cannot be accessed by those without appropriate authorization, for example if a security management subsystem can monitor users logging on to a network resource and can refuse access to those who enter inappropriate access codes.

Also Learn About Network Cabling