• Skip to main content
  • Skip to primary sidebar
  • Skip to secondary sidebar
  • Skip to footer

Computer Notes

Library
    • Computer Fundamental
    • Computer Memory
    • DBMS Tutorial
    • Operating System
    • Computer Networking
    • C Programming
    • C++ Programming
    • Java Programming
    • C# Programming
    • SQL Tutorial
    • Management Tutorial
    • Computer Graphics
    • Compiler Design
    • Style Sheet
    • JavaScript Tutorial
    • Html Tutorial
    • Wordpress Tutorial
    • Python Tutorial
    • PHP Tutorial
    • JSP Tutorial
    • AngularJS Tutorial
    • Data Structures
    • E Commerce Tutorial
    • Visual Basic
    • Structs2 Tutorial
    • Digital Electronics
    • Internet Terms
    • Servlet Tutorial
    • Software Engineering
    • Interviews Questions
    • Basic Terms
    • Troubleshooting
Menu

Header Right

Home » Networking » Addressing » Public IP Address – What Is a Public IP Address?
Next →
← Prev

Public IP Address – What Is a Public IP Address?

By Dinesh Thakur

An IP address is considered public if the IP number is valid and falls outside any of the IP address ranges reserved for private uses by Internet standards group. Public IP addresses are used by servers (including those for Web sites and DNS servers), network routers or any computer connected directly to the Internet via a modem.

Each public IP is assigned to a range or block of addresses. The Internet Assigned Numbers Authority (IANA) controls ownership of these IP ranges and assigns each block to organizations such as Internet Service Providers (ISPs) who in turn allocate individual IP address to customers.

Address Resolution Protocol (ARP) is a protocol for mapping an Internet Protocol address (IP address) to a physical machine address that is recognized in the local network. For example, in IP Version 4, the most common level of IP in use today, an address is 32 bits long.

In an Ethernet local area network, however, addresses for attached devices are 48 bits long. (The physical machine address is also known as a Media Access Control or MAC address.) A table, usually called the ARP cache is used to maintain a correlation between each MAC address and its corresponding IP address. ARP provides the protocol rules for making this correlation and providing address conversion in both directions.

How ARP Works

When an incoming packet destined for a host machine on a particular local area network arrives at a gateway, the gateway asks the ARP program to find a physical host or MAC address that matches the IP address. The ARP program looks in the ARP cache and, if it finds the address, provides it so that the packet can be converted to the right packet length and format and sent to the machine.

If no entry is found for the IP address, ARP broadcasts a request packet in a special format to all the machines on the LAN to see if one machine knows that it has that IP address associated with it. A machine that recognizes the IP address as its own returns a reply so indicating. ARP updates the ARP cache for future reference and then sends the packet to the MAC address that replied.

Since protocol details differ for each type of local area network, there are separate ARP Requests for Comments (RFC) for Ethernet, ATM, Fiber Distributed-Data Interface, HIPPI, and other protocols.

There is a Reverse ARP (RARP) for host machines that don’t know their IP address. RARP enables them to request their IP address from the gateway’s ARP cache.

The most widely used network layer protocol in the world—by far—is the TCP/IP Internet Protocol. It’s no surprise then, that the most important address resolution protocol is the TCP/IP protocol bearing the same name as the technique itself: the Address Resolution Protocol (ARP).

ARP is a full-featured dynamic resolution protocol used to match IP addresses to underlying data link layer addresses. Originally developed for Ethernet, it has now been generalized to allow IP to operate over a wide variety of layer two technologies.

In this section I describe the operation and features of ARP. I begin with an overview of the protocol, and a discussion of its defining standards and history. I briefly outline how addresses are specified in ARP and its general operation, as well as describing the message format used for ARP messages.

I then turn to the important matter of caching in ARP and how that is used to improve performance. I conclude with a discussion of proxying in ARP, which is needed to support special network connectivity situations.

You’ll also like:

  1. Write A C++ Program To Assign The Public Object Member Address To A Pointer.
  2. What is IP Address? Types of IP Address
  3. Private IP Address – What is a Private IP Address?
  4. IP Address Classes or Classful addressing
  5. What is MAC address (Media Access Control)? – Definition
Next →
← Prev
Like/Subscribe us for latest updates     

About Dinesh Thakur
Dinesh ThakurDinesh Thakur holds an B.C.A, MCDBA, MCSD certifications. Dinesh authors the hugely popular Computer Notes blog. Where he writes how-to guides around Computer fundamental , computer software, Computer programming, and web apps.

Dinesh Thakur is a Freelance Writer who helps different clients from all over the globe. Dinesh has written over 500+ blogs, 30+ eBooks, and 10000+ Posts for all types of clients.


For any type of query or something that you think is missing, please feel free to Contact us.


Primary Sidebar

Networking

Networking Tutorials

  • Network - Home
  • Network - Uses
  • Network - Advantages
  • Network - Classification
  • Network - Architecture Type
  • Nework - Networks Vs Comms

Networking Devices

  • Network - Modem
  • Network - Routers Types
  • Network - Bluetooth
  • Network - RS-232C
  • Network - Hub
  • Network - Devices
  • Network - Bridges
  • Network - Repeaters
  • Network - Routers
  • Network - Switching Hubs
  • Network - Transceiver
  • Network - Multiplexer
  • Network - Gateway
  • Network - BNC Connector
  • Network - Optical Connectors
  • Network - NICs
  • Networking Protocol

  • Protocol - Definition
  • Protocol - IP
  • Protocol - Aloha
  • Protocol - MAC Layer
  • Protocol - Sliding Window
  • Protocol - Stop & Wait
  • Protocol - Network Protocols
  • Protocol - Token Passing
  • Protocol - SIP
  • Protocol - Ad-Hoc Networks Routing
  • Protocol - Lap-f
  • Protocol - Point-to-Point
  • Protocol - PPP
  • Protocol - PPP Phases
  • Protocol - LDP
  • Protocol - MPLS
  • Protocol - MPOA
  • Protocol - HDLC
  • Protocol - Distance Vector routing
  • Protocol - IGMP
  • Protocol - ICMP
  • Protocol - SLIP
  • Protocol - DVMRP
  • Protocol - SDLC
  • Protocol - Routing
  • Protocol - UDP
  • Protocol - ARP and RARP
  • Protocol - Link-State
  • Protocol - ARP Table
  • Protocol - RTP
  • Protocol - NHRP
  • Network Addressing

  • Addressing - Home
  • Addressing - SubNetting
  • Addressing - Classless
  • Addressing - Classes or Classful
  • Addressing - IPV4 vs IPV6
  • Addressing - IPv6
  • Addressing - Subnet Mask
  • Addressing - MAC Address
  • Addressing - Supernetting
  • Addressing - Private IP
  • Addressing - IPv4
  • Addressing - Public IP
  • Addressing - Multihomed
  • Addressing - Indirect Addressing
  • Addressing - ASP
  • Addressing - VLSM
  • Addressing - Routing Algorithms
  • Addressing - Hierarchical Routing
  • Addressing - Routing
  • Addressing - Distributed Routing
  • Addressing - Data Routing
  • Addressing - Services
  • Addressing - IP forwarding
  • Addressing - Aging
  • Addressing - Algorithm CR
  • Networking Media

  • Transmission - Home
  • Transmission - Modes
  • Transmission - Media
  • Transmission - System
  • Transmission - Bound
  • Transmission - Unbound
  • Transmission - Baseband
  • Transmission - Wired
  • Transmission - Fiber Benfits
  • Transmission - Infrared
  • Transmission - UnGuided
  • Transmission - Microwave
  • Transmission - Infrared
  • Transmission - Radio Wave
  • Transmission - Network
  • Transmission - Digital Signal
  • Transmission - Data
  • Transmission - Asynchronous
  • Transmission - Sync Vs Async
  • Cable - Twisted-Pair
  • Cable - Coaxial
  • Cable - UTP and STP
  • Cable - Fiber Optics
  • Cable - Gigabit Ethernet
  • Cable - Fast Ethernet
  • Cable - Ethernet Cable
  • Cable - Fiber-Optic Using
  • Cable - CATV
  • Cable - 100Base T
  • Cable - 10BASE T
  • Cable - 10 Base 2
  • Cable - 10 Base 5
  • Networking Types

  • IEEE - 802.11
  • IEEE - 802.5
  • IEEE - 802.15
  • IEEE - 802.11e
  • IEEE - 802.11n
  • Network - Ethernet
  • Network - Arpanet
  • Network - Frame Relay
  • Network - X.25
  • Network - Telephone
  • Network - WSN
  • Network - Metro Ethernet
  • Network - WAN Ethernet
  • Network - Wireless Mesh
  • Network - SAN
  • Network - SNA
  • Network - Cisco Architecture
  • Network - Vlan
  • Network - FDDI
  • Network - 100VG-Any
  • Network - EPON
  • Network - ISDN
  • Network - ARCNet
  • Network - Passive Optical
  • Networking Reference Models

  • Models - TCP/IP
  • Models - OSI
  • Models - MAC Layer
  • Models - Network Layer
  • Models - MAC Layer Functions
  • Models - TCP/IP Vs OSI
  • Models - CSMA
  • Models - CSMA/CD
  • Models - CSMA/CA
  • Models - CDMA
  • Models - STDM
  • Models - FDMA
  • Models - TDMA
  • Models - SDH
  • Models - CDM
  • Models - Multiplexing
  • Models - Reference
  • Models - Random Access Methods
  • Models - TCP/IP Architecture
  • Models - FDM
  • Models - IP Header
  • Models - OTN
  • Models - Amplitude Levels
  • Models - MIMO
  • Models - Plesiochronous Media
  • Models - Half Duplex
  • Models - ISO Architecture
  • Models - Data-Link Layer
  • Models - WDM
  • Models - Duplex
  • Models - Ethernet FDSE
  • Networking Switching Techniques

  • Switching - Home
  • Switching - Techniques
  • Switching - Packet
  • Switching - Circuit
  • Switching - Message
  • Switching - Packet Vs virtual Circuit
  • Switching - Cell
  • Switching - ATM Cell Structure
  • Switching - Virtual Circuit Vs Datagram
  • Switching - Time Space
  • Switching - Modulation
  • Switching - Cell Relay
  • Switching - ATM Structure
  • Switching - VC Vs PVC
  • Switching - Packet and Circuit
  • Switching - VPC
  • Switching - IP
  • Switching - Logical Channels
  • Switching - TDM
  • Switching - FDM
  • Network Codes

  • Codes - CRC
  • Codes - Error Correction and Detection
  • Codes - Hamming
  • Codes - Piggybacking
  • Codes - Encoding Techniques
  • Codes - Error Control
  • Codes - Parity Check
  • Codes - Parity bit
  • Codes - Bit Error
  • Codes - CRC
  • Codes - Transmission Errors
  • Codes - Error Detection and Correction
  • Network Communication

  • Communication - Home
  • Communication - Satellite
  • Communication - Wireless
  • Communication - Data Type
  • Communication - Congestion Control
  • Communication - Network
  • Communication - Data
  • Communication - Software
  • Communication - Layering Process
  • Networking Signaling

  • Signal - Analog
  • Signal - Digital
  • Signal - Analog Vs Digital
  • Signal - Digitization
  • Network Security

  • Security - Home
  • Security - Requirements
  • Security - Threats
  • Security - Services

Other Links

  • Networking - PDF Version

Footer

Basic Course

  • Computer Fundamental
  • Computer Networking
  • Operating System
  • Database System
  • Computer Graphics
  • Management System
  • Software Engineering
  • Digital Electronics
  • Electronic Commerce
  • Compiler Design
  • Troubleshooting

Programming

  • Java Programming
  • Structured Query (SQL)
  • C Programming
  • C++ Programming
  • Visual Basic
  • Data Structures
  • Struts 2
  • Java Servlet
  • C# Programming
  • Basic Terms
  • Interviews

World Wide Web

  • Internet
  • Java Script
  • HTML Language
  • Cascading Style Sheet
  • Java Server Pages
  • Wordpress
  • PHP
  • Python Tutorial
  • AngularJS
  • Troubleshooting

 About Us |  Contact Us |  FAQ

Dinesh Thakur is a Technology Columinist and founder of Computer Notes.

Copyright © 2025. All Rights Reserved.

APPLY FOR ONLINE JOB IN BIGGEST CRYPTO COMPANIES
APPLY NOW