Computer Network Tutorial

Introduction of Computer Network Types of Computer Network Network Topology Computer Networking Architecture Transmission Modes (Data Flow) Basic Networking Devices Integrate Services Digital Network (ISDN)


OSI Model TCP/IP Model

Physical Layer

Digital Transmission Analog Transmission Transmission Media Switching

Data Link Layer

Error detection and Error correction Data Link Control Multiple Access Aloha

Network Layer

Network Layer - Logical Address Address Mapping Unicast Routing Protocol

Transport Layer

Process to Process Delivery User Datagram Protocol Transmission Control Protocol Stream Control Transmission Protocol Session Layer and Presentation Layer

Application Layer

Domain Name System Application Protocol E-mail Cryptography

Internet Protocol

Ipv4 vs Ipv6 Supernetting in Network Layer TCP Ports TCP vs UDP TCP TCP Congestion


Differences between IPv4 and IPv6 Difference between Active and Passive FTP Difference between Transport and Network Layer Difference between Star Topology and Bus Topology Difference between BOOTP and RARP Difference Between Network Topologies and Network Protocols Difference between NFC and RFID Difference Between Point-to-Point Link and star Topology Network Differences Between MSS and MTU Differences Between Trunk Port and Access Port Different Modes of Communication in Computer Networks Difference Between Analog and Digital Signals Difference Between Hub and Repeater Difference between Repeater and Switch Difference Between Transparent Bridge and Source Routing Bridge Difference between Border Gateway Protocol (BGP) and Routing Information Protocol (RIP) Difference between GUI Testing and Usability Testing Difference between Sanity Testing and Smoke Testing Differences between Distance Vector and Link State Routing Difference Between Intranet and VPN Difference between VLAN and VSAN


APIPA What is Computer Network What is Framing in a Computer Network What is Bus Topology What is Network Topology and Types in Computer Networks What is a Proxy Server What is APPN What is ICMP Protocol What is Point-to-Point Protocol What is Port Address in Networking What is the HDLC Protocol What is VRRP Protocol What is Wired and Wireless Networking What is a Hardware Firewall What is PAN What is Unit Testing? Why developers should learn Unit Testing What is Data Encapsulation and Data Decapsulation in Networking What is Macro Virus and how they affect Computer Systems What is VLAN What is VSAN What is WSN Network What is Cidr in AWS What are Elementary Data Link Layer Protocols What is An Ad Hoc Network What is The Ieee 802 What is Tunneling in Computer Networks What is Twisted Pair Cable What is a Computer Network What is an ISP


Classes of Routing Protocols Classification of Routing Algorithms Controlled Access Protocols in Computer Networks Fixed and Flooding Routing Algorithms Advantages and Disadvantages of Fibre Optics Cable Fiber Optics and its Types Method of Joining and Fusion of Fiber Optic Cable Define Framing in Computer Network Disadvantages of Computer Network Mesh Topology Diagram in Computer Network Ring Topology in Computer Network Star Topology in Computer Networks 4G Mobile Communication Technology Advantages and Disadvantages of LAN Advantages and Disadvantages of MAN Advantages and Disadvantages of WAN Application Layer in OSI Model Cyclic Redundancy Check Example Data link layer in OSI model Hamming Code Example Network Layer in OSI Model Session Layer in OSI Model Transport Layer in OSI Model Two Port Network in Computer Networks Uses of Computer Networks Advantages and Disadvantages of Bus Topology Subnetting in Computer Network Subnetting Questions and Answers Access Control in Networking Basic Characteristics of Computer Network Benefits of SOCKS5 Proxy in Computer Networks Computer Network viva Questions MIME Protocol in Computer Networks Modes of Communication in Computer Networks Network Attack in Computer Network Port Address in Networking Simplest Protocol in Computer Network Sliding Window Protocol in Computer Network Stop And Wait Protocol in Computer Networks TCP 3-Way Handshake Process in Computer Networks Source Routing Bridge in Computer Networks Transparent Bridge in Computer Networks Transport Protocol in Computer Networks Types of CSMA in Computer Networks Bit Stuffing and Bit De-Stuffing Firewall Methodologies Go Back ARQ in Computer Network Zone Based Firewall Advantages and Disadvantages of Mesh Topology Advantages and Disadvantages of Ethernet Advantages and Disadvantages of Ring Topology Advantages and Disadvantages of the Star Topology Checksum in Networking Delays in Computer Network Functions of Data Link Layer in the OSI Model Go-Back-N ARQ Protocol Guided Transmission Media in Computer Networks IGRP Routing Protocol in Computer Networks Modes Of Bluetooth Connection Protocols of a Network Layer Single Program Multiple Data Data Transfer Instructions with Examples Levels of Cache Memory Logical Addressing in Computer Network Multiple Access Protocols in Computer Network Advantages of Unguided Media Back Side Bus in Computer Network Router and Brouter in Computer Network 2 Dimension Parity Check in Computer Network Data Link Layer Services Provided to the Network Layer Functions Of the Transport Layer Computer Network Security Requirements Transmission Impairments in Computer Networks Types of Modems Microwave Transmission in Computer Networks Brust Errors In Computer Network Digital Signal in Computer Network Network Security Requirements Router in Computer Network Check Sum Error Detection Checksum Example Infrared Transmission in Computer Networks Linear Bus Topology Magnetic Media in Computer Network Digital Data Transmission in Computer Networks Advantages and Disadvantages of Routers Advantages of Installing a Network Application Layer in Computer Networks Application Layer Protocols in Computer Networks Application of Data Communication Network Central Device in Star Topology Multiple Access Techniques in Wireless Communication Parallel Port in Computer Resource Sharing in Computer Networks Static Routing Algorithms in Computer Network TDMA Technology Advantages and Disadvantages of Networking ATM Network Authentication in Computer Network Automatic Repeat Request Arq Characteristics of Digital Signals Cim Data Transmission Methods Components of Data Communication in Computer Network Disadvantages of Tree Topology DVRMP in Computer Network Mac Layer Functions and Protocol Pros and Cons of Extranet Protocol and its Types Resource Sharing in Computer Network Simplex Data Transmission in Computer Network Top 10 Benefits of Computer Networking Types of Computer Buses Unguided Media

Working of ARP

The majority of computer programmes and applications send and receive messages using logical addresses (IP addresses), but the actual communication takes place over physical addresses (MAC addresses), which is found in layer 2 of the OSI model.

Our objective is to find the destination MAC address so that we can communicate with other devices. Because ARP transforms IP addresses into Mac addresses or physical addresses, which is helpful in this situation.

A new computer that joins a LAN is specified by a special IP address that is used for identification and communication. The ARP program will be asked to locate a MAC address that matches the IP address when a packet is incoming from a host computer on a particular LAN reaches the gateway.

A host first determines whether the IP to Mac address translation is present or not in the ARP cache when it requests a MAC address to send a packet to another host in the LAN. If it exists, a new ARP request is not required and if the translation is not exist a request for network addresses is sent before an ARP operation.

ARP sends a request packet to every device on the LAN if any LAN machine use the particular IP address.

The ARP Request message will be broadcast throughout the local network by the source computer. Every device connected to the LAN network receives the broadcast message.

Instead of being broadcast, the ARP Reply message is unicast. This is so because the device from which the ARP Reply message is being sent is aware of the MAC address of the device from which the message is being received.

The destination's MAC address will be updated by the source in the ARP cache. The sender can now communicate with the receiver directly.

Network devices transfer the packet to the network layer after removing the frame's protocol data unit (PDU) called the data link layer's header (layer 3 of OSI).

If the network IDs of the source and destination IPs match, the destination's MAC address is returned to the source, otherwise, the packet reaches the network gateway, which broadcasts it to the connected devices and verifies their network IDs.

The above-said procedure continues up until the second last network device in the path arrives at the destination, at which point it is validated and ARP replies with the destination MAC address.

The request message or field in ARP contains many important terms like:

1. Hardware Type: It describes the type of hardware that is used to send the ARP message.The most popular kind of hardware is Ethernet.

2. Protocol Type: It describes the protocol type (hex, decimal, etc.) Each protocol is specified as a number. And in this case, the IPv4 protocol is a hex type protocol which is commonly used.

3. Protocol Size: It describes the length or size of the protocol. Here the size of the IPv4 address is 4 bytes.

4. Opcode: It describes the ARP message's code or nature. For Example, 1 represents an ARP request, and 2 represents an ARP response.

5. Source IP Address: It contains source IP address like

6. Destination(Target) IP Address: It contains a destination IP address like

7. Source MAC Address: It contains Source Mac Address like 00:1a:6b:6c:0c:cc

Advantages Of ARP

  • The main benefit of a proxy ARP is that it can communicate with every machine on the network with the help of one router.
  • If we are aware of the device's IP address, we can quickly determine the MAC address of that device by using ARP.
  • It is not necessary to set the end nodes addresses for the MAC address. If necessary, we can locate it.

Disadvantages of ARP

  • The main drawback is that hosts on a network build up more information in their ARP tables because they believe that all other machines are reachable via an ARP request.
  • It boosts ARP traffic in your segment.
  • Larger ARP tables are required by hosts to manage IP-to-MAC address mappings.
  • Security threats are possible.
  • Networks without ARP-based address resolution are not supported by it.
  • It does not apply to every network topology.

Why is ARP important?

ARP is required because it converts the host software address into a hardware address (MAC address). A host is unable to determine the hardware address of another host without the use of ARP. The local area network (LAN) maintains a table or directory that converts IP addresses to MAC addresses for various devices, including routers and endpoints.

Users or even IT administrators are not responsible for maintaining this table or directory. Instead, the ARP protocol generates entries when required.

ARP Spoofing

ARP spoofing is also known as ARP poison routing and ARP cache poisoning. In this malicious attack, a hacker sends phony ARP messages to a target LAN in an effort to associate their MAC address with the IP address of a reliable server or device on the network.

Data from the victim's computer can be sent through the link to the attacker's machine instead of the original destination. Attacks using ARP spoofing can be risky because sensitive data may be transferred between computers without the victim's knowledge.


Our objective is to find the destination MAC address so that we can communicate with other devices. Because ARP transforms IP addresses into Mac addresses or physical addresses, which is helpful in this situation.