{"id":3051,"date":"2025-10-04T23:28:50","date_gmt":"2025-10-04T16:28:50","guid":{"rendered":"https:\/\/kienthucmo.com\/what-is-an-ip-address-fundamental-knowledge-and-practical-applications\/"},"modified":"2026-01-14T23:39:11","modified_gmt":"2026-01-14T16:39:11","slug":"what-is-an-ip-address-fundamental-knowledge-and-practical-applications","status":"publish","type":"post","link":"https:\/\/kienthucmo.com\/en\/what-is-an-ip-address-fundamental-knowledge-and-practical-applications\/","title":{"rendered":"What Is an IP Address? Fundamental Knowledge and Practical Applications"},"content":{"rendered":"\n

In the digital age, almost every day we connect to the Internet – from browsing the web, watching YouTube, and using social media to sending emails or making intercontinental video calls. But have you ever wondered how a laptop at home can communicate with a server located in the United States, or how the phone in your pocket can send a message all the way to Europe?\r\n<\/p>\n\n\n\n

The answer lies in a concept that may seem simple but is extremely important: the IP address. If we think of the Internet as a gigantic city, then an IP address is like a house number – an electronic identity that allows devices to find each other. Without IP addresses, the Internet would be nothing more than a tangle of cables and meaningless signals.<\/p>\n\n\n\n

In this article, I will explore the IP address with you in detail: what it is, how it works, how many types there are, why IPv4 and IPv6 exist, and why understanding IP is important not only for IT professionals but for anyone who uses the Internet on a daily basis.<\/p>\n\n\n\n

\"What<\/figure>\n\n\n\n

1. Overview of IP Addresses<\/h2>\n\n\n\n

1.1. What Is an IP Address?<\/h3>\n\n\n\n

An IP address (Internet Protocol Address) is a sequence of numbers assigned to each device in a computer network. It serves as an identifier, enabling devices to \u201crecognize\u201d one another and exchange data accurately.\r\n<\/p>\n\n\n\n

You can imagine the Internet as a gigantic city, and each device (computer, phone, server, camera, etc.) as a house. Without an address, the mail carrier (data packets) would not know where to deliver the mail. An IP address is the \u201chome address\u201d in the digital world.<\/p>\n\n\n\n

A data packet traveling on the Internet always contains a source IP (the address from which it is sent) and a destination IP (the address of the recipient). Thanks to this, information can travel around the world and still return to the correct computer.<\/p>\n\n\n\n

Example:<\/strong><\/p>\n\n\n\n

When you type www.google.com<\/a><\/strong>, the DNS translates this domain name into an IP address, for example 192.168.190.14<\/strong>. Thanks to this, the browser can establish a connection with Google\u2019s server.<\/pre>\n\n\n\n
1.2. The Role of IP in Computer Networks<\/h3>\n\n\n\n
An IP address has two extremely important roles:<\/p>\n\n\n\n
    \n
  • Device identification:<\/strong> Like an identity card, an IP address is unique within a network. Without an IP address, it would be impossible to determine which device is \u201cmachine A\u201d or \u201cmachine B.\u201d<\/li>\n\n\n\n
  • Data routing:<\/strong> Imagine sending a parcel from Hanoi to New York. Along the way, it passes through many checkpoints (routers). The IP address acts as a \u201croad map,\u201d allowing the data packet to know which direction to take at each next step.<\/li>\n\n\n\n
  • Global communication:<\/strong> Thanks to IP addresses, a computer in Vietnam can send emails to the United States, or a smartphone can make video calls to Japan.<\/li>\n<\/ul>\n\n\n\n
    Without IP addresses, the Internet would be nothing more than a tangle of cables and \u201csilent\u201d computers, with no way for devices to recognize one another.<\/p>\n\n\n\n
    1.3. Classification of IP Addresses<\/h3>\n\n\n\n
    In practice, IP addresses are classified in several ways. Some common classifications include:\r\n<\/p>\n\n\n\n
    a) By scope of use<\/h4>\n\n\n\n
      \n
    • Private IP (internal IP):<\/strong>
      Used within a LAN (local network). Examples include 192.168.x.x<\/strong> and 10.x.x.x<\/strong>.
      \u2192 These addresses are used for devices within a home or company network to communicate with each other and do not connect directly to the Internet.<\/li>\n\n\n\n
    • Public IP:<\/strong>
      Assigned by an Internet Service Provider (ISP). This is the address that is \u201cvisible\u201d on the Internet.
      \u2192 For example, when you search on Google for \u201cwhat is my IP,\u201d the address you see is your Public IP.<\/li>\n<\/ul>\n\n\n\n
      b) By stability<\/h4>\n\n\n\n
        \n
      • Static IP:<\/strong> An address that does not change over time. It is commonly used for web servers and email servers.<\/li>\n\n\n\n
      • Dynamic IP:<\/strong> An address that changes each time you connect to the Internet. Regular users are typically assigned this type of IP to conserve the number of available addresses.<\/li>\n<\/ul>\n\n\n\n
        \"Classification<\/figure>\n\n\n\n
        c) IPv4 vs IPv6<\/h4>\n\n\n\n
          \n
        • IPv4:<\/strong> Introduced earlier, with a length of 32 bits, providing a maximum of about 4.3 billion addresses.<\/li>\n\n\n\n
        • IPv6:<\/strong> Introduced later, with a length of 128 bits, offering an almost unlimited number of addresses.<\/li>\n<\/ul>\n\n\n\n
          Easy-to-Understand Real-World Example<\/h3>\n\n\n\n
          Assume your home has Wi-Fi. The router assigns each device a Private IP (for example: Laptop \u2013 192.168.1.2<\/strong>, Smartphone \u2013 192.168.1.3<\/strong>). However, when accessing the Internet, both devices are \u201chidden\u201d behind a single Public IP assigned by the ISP (for example: 203.113.45.67<\/strong>).<\/p>\n\n\n\n
          The router acts like a \u201cgatekeeper,\u201d translating and forwarding data between Private IP addresses and the Public IP address. This mechanism is called NAT (Network Address Translation). Thanks to NAT, despite the limitations of IPv4, we are still able to connect millions of devices to the Internet.<\/p>\n\n\n\n
          2. Structure of an IP Address<\/h2>\n\n\n\n
          2.1. Structure of an IPv4 Address<\/h3>\n\n\n\n
          \"Structure<\/figure>\n\n\n\n
          a) Representation format<\/h4>\n\n\n\n
          IPv4 consists of 32 bits (that is, 4 bytes). To make it easier for humans to read, it is divided into four groups (called octets), each octet being 8 bits, and then written in decimal numbers separated by dots.<\/p>\n\n\n\n
          Example:<\/p>\n\n\n\n
            \n
          • Binary: 11000000 10101000 00000001 00001010<\/strong><\/li>\n\n\n\n
          • Decimal: 192.168.1.10<\/strong><\/li>\n<\/ul>\n\n\n\n
            Each octet has a value from 0 to 255, so IPv4 ranges from 0.0.0.0<\/strong> to 255.255.255.255<\/strong>.<\/p>\n\n\n\n
            b) Division into Network ID and Host ID<\/h4>\n\n\n\n
            An IPv4 address consists of two parts:<\/p>\n\n\n\n
              \n
            • Network ID:<\/strong> Identifies the network.<\/li>\n\n\n\n
            • Host ID:<\/strong> Identifies the device (host) within that network.<\/li>\n<\/ul>\n\n\n\n
              Example:<\/p>\n\n\n\n
                \n
              • Address: 192.168.1.10<\/strong><\/li>\n\n\n\n
              • Subnet Mask: 255.255.255.0<\/strong>
                \u2192 The first three octets (192.168.1<\/strong>) are the Network ID, and the last octet (10<\/strong>) is the Host ID.<\/li>\n<\/ul>\n\n\n\n
                Thus, all IP addresses 192.168.1.x<\/strong> (where x<\/strong> ranges from 1 to 254) belong to the same network.<\/p>\n\n\n\n
                c) Special Addresses in IPv4<\/h4>\n\n\n\n
                  \n
                • Network address:<\/strong> Host ID = 0 (for example, 192.168.1.0<\/strong>).<\/li>\n\n\n\n
                • Broadcast address:<\/strong> Host ID = all bits set to 1 (for example, 192.168.1.255<\/strong>).<\/li>\n\n\n\n
                • Loopback address:<\/strong> 127.0.0.1<\/strong> \u2013 used for a computer to communicate with itself.<\/li>\n<\/ul>\n\n\n\n
                  d) Subnet Mask and CIDR<\/h4>\n\n\n\n
                  To distinguish between the network part and the host part, a Subnet Mask is used.
                  For example:<\/p>\n\n\n\n
                    \n
                  • Subnet Mask: 255.255.255.0<\/code><\/li>\n\n\n\n
                  • CIDR notation: \/24<\/strong> (meaning the first 24 bits are for the network, and the remaining 8 bits are for the host).<\/li>\n<\/ul>\n\n\n\n
                    CIDR (Classless Inter-Domain Routing) allows for more flexible network subdivision compared to the traditional class-based addressing of Classes A, B, and C.\r\n<\/p>\n\n\n\n
                    2.2. Structure of an IPv6 Address<\/h3>\n\n\n\n
                    \"Structure<\/figure>\n\n\n\n
                    IPv6 is 128 bits long, divided into 8 groups, with each group consisting of 16 bits. It is represented in hexadecimal (base 16) to make it more compact, with groups separated by colons (\u201c:\u201d).<\/p>\n\n\n\n
                    Example:<\/p>\n\n\n\n
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