Product Attribute Selection
Last updated:2026-01-08 17:28:09
On CLB purchase page, you can select CLB instances of different attributes. This document describes how to purchase instances based on business scenarios.
Regions
We recommend selecting the region closest to your client to reduce delay and accelerate the download speed.
CLB can only forward traffic to CVM instances in the same region. Please select the region where your CVM instance is located before creating a CLB instance.
CLB can forward traffic to CVM instances in multiple availability zones in the same region.
A public network CLB (formerly "application CLB") instance supports cross-region binding of CVM. You can select the region of real servers and bind them across VPCs or regions. For example, you can bind a CLB instance in Beijing to a CVM instance in Shanghai to forward the client traffic to the latter. For more information, please see CLB Instance Cross-Region Binding.
Instance Types
CLB instances can be classified into two types: CLB (formerly "application CLB") and classic CLB. CLB covers all features of classic CLB. Based on product features and performance, we recommend CLB. For a detailed comparison, please see Instance Types.
Network Types
Public network CLB
If you need to use CLB to distribute requests from the public network, please select "Public Network".
Public network CLB instances obtain requests from the client via the internet and distribute them to the bound real servers.
Domain name-based public network CLB (recommended): Tencent Cloud assigns a domain name to CLB. Users can resolve their own domain names to the assigned domain name by adding a CNAME record through the DNS resolution service. This enhances availability, increasing the SLA from 99.95% to 99.99%, and supports the replacement of faulty VIP addresses to minimize impact on customer business. It also offers better elasticity with auto scaling based on business requests, flexible horizontal scale-out, and larger specifications.
Non-domain-name-based public network CLB: Tencent Cloud assigns a VIP address to CLB. Users can resolve their own domain names to the assigned VIP by adding an A record through the DNS resolution service. The VIP address is fixed and cannot be switched.
Use Cases
A server cluster is used to provide services to public networks. A unified entry is required, while requests from users of public networks should be assigned to server clusters.
Users of different ISPs are connected to networks closest to them to accelerate network access.
Public VIP types
Regular IP: Regular BGP IP, which is suitable for users want to balance the network quality and cost.
Single-line IP: Accessing the public network via a single ISP, which is low-cost and convenient for self-scheduling.
Billing
For a bill-by-CVM account, only the instance fee is charged for purchasing a public network CLB instance. The service fees incurred by public network bandwidth and traffic are charged on its real server. For more information, please see Bill-by-CVM Account Billing Description.
For a bill-by-IP account, the instance fee and public network fee are charged for purchasing a public network CLB instance. For more information, please see Bill-by-EIP/CLB Account Billing Description.
Private network CLB
If you need to use CLB to distribute requests from private networks, please select "Private Network".
Both the client and server of private network CLB are in Tencent Cloud and can only be accessed within Tencent Cloud. Access via the internet is not allowed (no public network IP address). Tencent Cloud will assign a private IP to CLB from the network you have selected (such as a VPC). The request traffic will be routed to the backend CVM instance via this IP address.
If your application has multiple layers, such as web servers that can communicate over the internet or database servers that can only communicate over the private network, you can create a framework with both public and private network CLB instances. You can then connect all web servers to the public network CLB instance and database servers to the private network CLB instance. The public network CLB instance receives requests from the internet and sends them to the backend web servers. After being processed, requests to database will be sent to the private network CLB instance, which will then route the requests to database servers.
Use Cases
Tencent Cloud has more than one internal servers. Requests from the client need to be allocated to servers properly.
Fault tolerance and restoration are needed for the internal server cluster.
The service provider wants to block their own physical IP addresses and provide imperceptible services to the client.
Billing
The usage of private network CLB instances incur charges. But you don't need to pay the related public network fee (For more information, please refer to CLB Price Changes). Only LCU-supported CLB instances will incur LCU usage fees. For more information, please refer to LCU Fees.
Note:
Tencent Cloud plans to upgrade the architecture of all CLB instances starting from 00:00:00, November 2, 2021 (UTC +8). After the upgrade, the guaranteed performance of each shared CLB instance will be increased to 50,000 concurrent connections, 5,000 new connections per second, and 5,000 QPS. The pricing for the newly architected CLB instances for both private and public network will be adjusted to 0.686 USD/day (1.029 USD/day in some regions). For more information, please refer to CLB Price Changes.
IP Versions
The IP version of a CLB instance. Available versions: IPv4, IPv6, and IPv6 NAT64.
IPv4 Version: Supported across all regions.
IPv6 Version: Only the pay-as-you-go model supports regions such as Guangzhou, Shanghai, Nanjing, Beijing, Chengdu, Chongqing, Hong Kong (China), Singapore, and Virginia. The IPv6 CLB is in beta. To use it, please submit a ticket.
IPv6 NAT64 Version: Supported exclusively in the regions of Beijing, Shanghai, and Guangzhou.
IPv6 implementations are still at the preliminary stage across the internet. In case of access failure, you can submit a ticket. SLA is not guaranteed during the beta test period.
Network
CLB supports classic network and VPC. CLB does not support network switching.
The classic network is a public network resource pool for all Tencent Cloud users. The private IPs of all CVMs are assigned by Tencent Cloud. You cannot customize IP ranges or IP addresses.
By contrast, the VPC is a logically isolated network space in Tencent Cloud. In a VPC, you can customize IP ranges, IP addresses, and routing policies. VPC is more suitable for use cases requiring custom configurations.
To provide you with better services, Tencent Cloud will fully upgrade the classic network. From January 31, 2022, resources cannot be created on the classic network. Services on the classic network are officially discontinued on December 31, 2022. These services are replaced with the corresponding VPC services.For more information, please refer to Ending Support for Classic Network.
ISP
CLB supports the following ISP types: BGP (multi-line), China Mobile, China Telecom, and China Unicom.
In pay-as-you-go billing mode, all of the above four options are supported.
The bandwidth unit price for BGP (multi-line) operator type is four times that of China Mobile, China Telecom, or China Unicom. For cost-sensitive operations, it is recommended to deploy with Mobile, Unicom, or Telecom. The bandwidth billing model for China Mobile, China Telecom, or China Unicom operator types only supports bandwidth packages. For pricing details, please refer to Bandwidth Package - BGP Bandwidth Package and Bandwidth Package - China Mobile/Unicom/Telecom Bandwidth Package.
Note:
Currently, the static single-line IP is supported only in Guangzhou, Shanghai, Nanjing, Jinan, Hangzhou, Fuzhou, Beijing, Shijiazhuang, Wuhan, Changsha, Chengdu, and Chongqing. For the support information in other regions, see the console. If you want to try it out, contact the sales rep for application. Once your application is approved, you can select an ISP (China Mobile, China Unicom, or China Telecom) on the purchase page.
Instance specification
The specifications for CLB instances support both shared instances and LCU-supported instances. For more information, please refer to Instance Specifications Comparison.
Instance Name
CLB instance name, which can contain 1 to 60 characters, supports letters, digits, Chinese characters, hyphens (-), underscores (_), and periods (.).
Purchase Quantity
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