FAQ

What is CNAME? Why must I configure it?

CNAME (Canonical Name Record) is a type of DNS record.

Function: After you add a domain in the console, VMRack assigns you a dedicated CNAME address (e.g., site.cdn.vmrack.com).

Why needed: CDN nodes are distributed globally, and IP addresses change dynamically. Through CNAME, the system can intelligently resolve the user's request to the nearest and fastest node IP based on their location and network status. If you do not configure CNAME, traffic cannot pass through the CDN network, and acceleration will not take effect.

What is the difference between Accelerated Domain (Domain) and Origin HOST (Origin Host)?

This is a common misunderstanding; their functions are completely different:

Accelerated Domain: The domain name users access in the browser (e.g., www.example.com).

Origin HOST: The value carried in the Host field of the HTTP header when the CDN node requests data from your origin server.

Default: Equals the Accelerated Domain.

Special Case: If your origin requires binding to a specific domain (e.g., Object Storage Bucket domain), or if the origin server hosts multiple virtual hosts, you must modify the Origin HOST to a domain name recognized by the origin server; otherwise, the origin may refuse access or return a 404/403 error.

What is Origin Fetch?

When a user visits a CDN node, if the node does not have the cached resource, or the cached resource has expired, the CDN node will initiate a request to your origin server to obtain the latest data. This process is called "Origin Fetch".

Is CDN billing based on "Bandwidth Peak" or "Actual Traffic"?

We adopt the more cost-effective Actual Traffic Billing (Traffic-based). Regardless of how many Mbps your bandwidth runs, we only calculate based on the actual amount of data transferred (GB). Compared to bandwidth billing, traffic billing is more suitable for businesses with obvious peaks and valleys, truly achieving "pay for what you use".

What is the monthly free quota? When does it refresh?

VMRack provides a 30 GB / month CDN free traffic package for all users, automatically resetting at 00:00 on the 1st of each month. Note: The free quota is used to offset traffic fees; unused quota for the current month cannot be rolled over to the next month.

How is CDN billed?

VMRack CDN uses a Pay-As-You-Go + Hourly Settlement model.

Settlement Cycle: The system settles the traffic costs generated in the previous hour every hour (on the dot).

Deduction Order: Prioritizes deducting the monthly 30GB free quota; after the quota is exhausted, it automatically deducts from the Account Credit.

What is the "Waived Amount" displayed in the bill?

This is a billing benefit provided to you by VMRack.

Reason: Our billing system is accurate to 4 decimal places, while actual payments are accurate to 2 places (cents).

Result: In the monthly unified settlement, the system automatically summarizes all unsettled fractional remainders. If the summarized total remainder is less than $0.01, the system will directly waive (write off) this fee, and you do not need to pay it.

What happens if I am in arrears?

When your account credit is less than 0, CDN services will be automatically stopped, you will be unable to access the CDN console, and connected sites will also stop accelerating. Please recharge to restore credit in time, and services will automatically recover.

I updated an image on the origin server, why do I still see the old image when accessing?

This is because the old file cached on the CDN node has not yet expired.

Solution: Go to Console > Site Management > Purge Cache, enter the URL of the updated file to refresh. After a successful refresh, the CDN node will immediately force an origin fetch to retrieve the latest file.

Long-term Advice: In "Cache Optimization", avoid frequent changes to files (like index.html) or set a longer cache time for them.

A 502 Bad Gateway error occurs after configuration, what should I do?

This is usually caused by improper Origin Protocol configuration.

Troubleshoot: Check if your origin server supports HTTPS.

If the origin only opens HTTP (Port 80), but you selected HTTPS in the CDN Origin Configuration, it will cause connection failure and a 502 error.

Fix: Change the Origin Protocol to HTTP.

How do I prevent my images from being stolen by other websites?

Please enable the Hotlink Protection function.

Enter the site details page's [Access Control] tab, enable Hotlink Protection and set the Allowlist. Enter your own domain name. This way, reference requests from non-whitelisted domain names will be directly rejected by the CDN.