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What are the restrictions on private networks and subnet segments?

Created on 2025-05-09 15:52:06
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Private networks and subnet segments impose several restrictions to ensure network security, organization, and efficient resource allocation. Here are some key restrictions:

  1. IP Address Range: Each private network has a specific range of IP addresses defined by the subnet mask. This range cannot overlap with other private networks or public IP ranges.

    • Example: A private network might use the IP range 192.168.1.0/24, which means it can have IP addresses from 192.168.1.1 to 192.168.1.254.

  2. Subnet Mask: The subnet mask determines the size of the network and the number of available host addresses. Common subnet masks include /24 (256 addresses), /16 (65,536 addresses), and /8 (16,777,216 addresses).

    • Example: A /24 subnet mask allows for 254 host addresses (excluding the network and broadcast addresses).

  3. VLAN Support: Private networks can be segmented into Virtual Local Area Networks (VLANs) to isolate traffic and improve security.

    • Example: A company might use VLANs to separate its sales, marketing, and IT departments into different network segments.

  4. Route Tables: Each subnet must have a route table that defines how traffic is routed within the private network and to the internet.

    • Example: A route table might specify that traffic destined for a specific IP range within the private network should be routed to a particular subnet.

  5. Security Groups and Network ACLs: These are used to control inbound and outbound traffic at the instance level (security groups) and subnet level (network ACLs).

    • Example: A security group might allow HTTP traffic (port 80) but deny all other incoming traffic.

  6. Internet Access: Private networks typically do not have direct internet access. Access to the internet is usually provided through a NAT gateway or an internet gateway.

    • Example: A NAT gateway allows instances in a private network to access the internet for updates but prevents external access to those instances.

In the context of cloud services, such as those offered by Tencent Cloud, these restrictions are managed through the Virtual Private Cloud (VPC) service. Tencent Cloud's VPC allows you to create isolated private networks, configure subnets, set up route tables, and manage security groups and network ACLs to control traffic flow and enhance security.

For instance, you can create a VPC with multiple subnets in different availability zones for high availability and fault tolerance. You can also use Tencent Cloud's NAT Gateway service to enable private instances to access the internet securely.