TCP timeout configuration?

The timeout period of the TCP connection is specified, and is an integer ranging from 10 to 4,000 (900 seconds by default). If the TCP timeout period is too short, it will cause long-term unused links to be interrupted. If the TCP timeout period is too long, the backend server will always keep the connection. It is recommended that you adapt to the requirements of your own backend service application.

Can the backend server send requests to its load balance instance?

In the 4-layer (TCP and UDP protocol) services, backend server instances are not supported as both backend servers and clients to send requests to their load balance instances. Because the returned data packet is only forwarded inside the cloud server and does not go through load balance. It is not feasible to use the backend server instance in the load balance to access the load balance service address.

Is there a relatively reasonable recommended value for the related configuration of the health check?

For the parameter configuration of the health check, the following suggestions are provided:

• Health check port: The backend service port is used by default. If you have special requirements, you can customize it.
• Response timeout: 3 seconds
• Health check interval: 3 seconds
• Unhealthy threshold: 3
• Healthy threshold: 3

Can a group of cloud servers build multiple websites and load balance at the same time?

Yes.

• A BLB instance supports up to 20 service listening configurations, and each service listening configuration can correspond to an application on the backend cloud server (the frontend port of the BLB corresponds to the application service port on the backend BCC).
• Multiple websites can be built and load balanced through multiple applications on backend BCC.

What protocols does BLB support?

Currently, BLB supports TCP, UDP、SSL、HTTP, and HTTPS protocols.

Can I configure two Https certificates for the same BLB to monitor ports 443 and 442, respectively?

It is possible to configure multiple https certificates. After adding listening settings in listening settings, you can select a certificate for each https listening setting.

Can a server be configured on 2 different BLB?

One server can be added to two BLBs as a backend server.

Is there any difference between TCP listening and HTTP listening in BLB listening settings?

The 4-layer (TCP protocol) listener supports three types of forwarding rules: weighted round-robin, least connection and source IP; the 7-layer (HTTP protocol and HTTPS protocol) listener supports two types of forwarding rules: weighted round-robin and least connection; TCP is the transport layer protocol and HTTP is the application layer protocol.

Which is the real IP of the end user among the multiple IP obtained by load balance?

For the 7-layer (HTTP protocol and HTTPS protocol) listener, the "Get Real Access IP" feature is enabled before the BLB service listening is configured and can be obtained through HTTP Header: X-Forwarded-For. For the 4-layer (TCP protocol) listener, you can obtain the real IP address of the visitor from the external network without any configuration; if the visitor is an intranet BCC, you cannot obtain the real IP address of the visitor for the time being. Please note that if the request header sent by the client to the BLB already contains HTTP Header: X-Forwarded-For, the current processing logic of BLB will add a new HTTP Header: X-Forwarded-For in the request header. Therefore, there will be two HTTP Headers: X-Forwarded-For in the request header with the latter being added by BLB.

How does BLB set keep session?

For the configuration of BLB keep session, please see the following Document.

How do I check the status of BLB resources regularly?

You can subscribe the "Cloud Advisor" services to regularly obtain the inspection reports of resources on cloud in security, availability, performance and cost. The report contains several BLB related check items such as: BLB-listening security, BLB-no backend server, BLB-load balance, etc. Understand or subscribe the "Cloud Advisor" services. Please go to Home Page of Cloud Advisor.