：The back-to-origin traffic of the Alibaba Cloud Content Delivery Network service is greater than the access traffic

Challenge

When you use Alibaba Cloud Content Delivery Network domain name acceleration, check that the back-to-origin traffic of the Alibaba Cloud Content Delivery Network service is greater than the access traffic in the Alibaba Cloud Content Delivery Network console.

Cause

• Gzip compression is not enabled for the origin server, and Gzip compression is enabled for Alibaba Cloud Content Delivery Network domain name acceleration.
• If the Range back-to-origin feature is not enabled, the back-to-origin traffic is large.

Modification method

1. For text and other types of content, the compression ratio of Gzip is relatively high. Therefore, if the origin server does not enable Gzip compression, but when the customer accesses the Alibaba Cloud Content Delivery Network, the Alibaba Cloud Content Delivery Network performs Gzip compression, the Alibaba Cloud Content Delivery Network back-to-origin bandwidth may be higher than the access bandwidth. After excluding this cause, you can check it through the next step.
2. Log on to the Alibaba Cloud Content Delivery Network console. In the left-side navigation pane, click Domain Names. On the Domain Names page, click Manage corresponding to the target domain name. In the left-side navigation pane of the specified domain name, click Video Related. In the Range Back-to-Origin section, click Modify to check whether the range back-to-origin feature is enabled. If this feature is not enabled, see Range back-to-origin.
3. In addition, when using Alibaba Cloud Content Delivery Network, some header information that Alibaba Cloud Content Delivery Network must use is added, such as the header of Via. Sometimes, Gzip has been set on the origin server, as shown in the following figure. If the
   
   but the request contains the header of Via, the origin server may not respond correctly to Gzip, as shown in the following figure. If this is the case, we recommend that you enable Gzip on the origin server. For more information, see More information.
   
   
   

References

Take the Nginx service as an example. Add the following content to the main configuration file of the Nginx service. Enable the Gzip rule for all Nginx origin settings.

gzip_proxied            any; 

Applicable scope

• CDN