IP addresses play a vital role in the process of building and maintaining network infrastructure. As two major types of IP addresses, public IP and private IP each have unique allocation mechanisms and usage restrictions. This article will analyze the differences between the two in detail to help readers better understand and apply IP addresses.

1. Overview of public IP and private IP

IP addresses are unique identifiers in the network, used to distinguish the locations of different devices in the network. Public IP addresses are assigned to users by Internet service providers (ISPs) and can uniquely identify a device worldwide to enable communication on the Internet. Private IP addresses are designed for use in internal organizational networks and will not be routed on the global Internet, ensuring the security of internal networks.

2. Allocation and usage restrictions of public IP addresses

Allocation mechanism

The allocation of public IP addresses mainly follows the IPv4 and IPv6 protocols. IPv4 addresses consist of 32-bit binary numbers and are divided into five categories. Class A, B, and C addresses are used for host addressing, Class D addresses are used for multicast communication, and Class E addresses are reserved for experimental purposes. IPv6 addresses are represented by 128-bit binary numbers, providing a larger address space to meet the needs of future network development.

Public IP addresses are usually allocated by ISPs. Users need to apply to and obtain a certain number of IP addresses from ISPs. ISPs will allocate appropriate IP address segments to users based on the size and needs of their networks.

Usage restrictions

Public IP addresses are unique globally, so the following points should be noted when using them:

(1) Avoid IP address conflicts: Due to the uniqueness of public IP addresses, devices in different networks cannot use the same IP address, otherwise communication failures will occur.

(2) Comply with network regulations: Users using public IP addresses need to comply with relevant Internet regulations and must not engage in illegal activities or attack other networks.

(3) Rational use of resources: Due to limited public IP address resources, users need to make reasonable use of allocated IP addresses to avoid waste.

3. Allocation and Usage Restrictions of Private IP Addresses

Allocation Mechanism

The allocation of private IP addresses follows the RFC 1918 standard, which defines three private IP address segments: 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16. These address segments are only used for internal networks of organizations and are not routed on the global Internet.

Private IP addresses are usually allocated by network administrators within the organization. The administrator will select a suitable address range from the private IP address segment for allocation based on the network size and needs.

Usage Restrictions

Private IP addresses are unique within the internal network, but not on the global Internet. Therefore, the following points should be noted when using private IP addresses:

(1) Avoid conflicts with public IP addresses: Although private IP addresses are unique within the internal network, care should still be taken to avoid conflicts with public IP addresses when configuring network devices.

(2) Limit access scope: Since private IP addresses are only used for internal networks, measures need to be taken to limit access to the internal network from external networks to ensure network security.

(3) Reasonable planning of network structure: When allocating private IP addresses, it is necessary to reasonably plan the network structure to ensure unimpeded communication between different network segments.

4. Summary

As two types of IP addresses, public IP and private IP have their own characteristics in address allocation and use. Public IP addresses are globally unique and can be used to achieve communication on the Internet; while private IP addresses are designed for use in internal organizational networks, ensuring the security of internal networks. In actual applications, users need to select the appropriate IP address type based on the network scale and needs, and comply with relevant specifications and usage restrictions to ensure the normal operation and security of the network.