This topic describes the limits that Alibaba Cloud CDN imposes on domain names. Before you add a domain name to Alibaba Cloud CDN, make sure that the domain name meets the requirements. This helps you prevent losses that can be caused by violations.

Item Description
Accelerated domain name
  • Domain name Type: The domain name to be accelerated can be a specific domain name such as example.aliyundoc.com or a wildcard domain name such as *.aliyundoc.com.
  • Format:
    • A domain name must be in lowercase letters such as example.com. Domain names that contain uppercase letters are invalid.
    • If the domain name contains Chinese characters such as 阿里云.网址, you must apply for an ICP number for the domain name in Chinese characters, and use the tool Punycode to convert the domain name to English letters, such as xn--fiq****.xn--eq****. Then, you can specify it as the domain name to be accelerated.
  • Requirements for wildcard domain names:
    • Alibaba Cloud CDN supports wildcard domain names. For more information about the limits on wildcard domain names, see Does Alibaba Cloud CDN support wildcard domain names?
    • The specified wildcard domain name and the domain names that match the wildcard domain name must belong to the same Alibaba Cloud account. If the problem persists, submit a ticket.
    • If a wildcard domain name is not added to Alibaba Cloud CDN, you can add domain names that match the wildcard domain name to Alibaba Cloud CDN by using different Alibaba Cloud accounts.
    • Each wildcard domain name can match up to 500 specific domain names. If more than 500 specific domain names are matched, only the first 500 specific domain names can acquire the settings of the wildcard domain name. Other domain names cannot be accelerated by Alibaba Cloud CDN.
      Note The first 500 specific domain names that match the wildcard domain name can be accelerated by Alibaba Cloud CDN.
  • You cannot add duplicate domain names to Alibaba Cloud CDN.

    If the system prompts that the domain name has been added to another Alibaba Cloud service, such as ApsaraVideo VOD or Dynamic Route for CDN (DCDN), you can submit ticket.

  • Each Alibaba Cloud account can add at most 50 domain names to Alibaba Cloud CDN.
    Note However, if the sum of the average daily peak bandwidth values of your domain names exceeds 50 Mbit/s, you can submit a ticket to add more domain names to Alibaba Cloud CDN. Make sure that the increase of domain names does not cause business risks.
  • The content delivered from the domain name must be legal and comply with the Terms of Service for Alibaba Cloud CDN. For more information about the limits, see Limits.
  • Length: A domain name cannot exceed 67 characters in length.
  • ICP filing: If the accelerated region of a domain name is set to Global or Mainland China Only, you must apply for an ICP number for the domain name. We recommend that you use Alibaba Cloud ICP Filing System to apply for ICP numbers.
  • Domain name reclaiming: If your domain name remains disabled for 120 days, Alibaba Cloud CDN automatically deletes the configuration records that are related to the domain name. This rule also applies to domain names that fail ownership verification. If you want to continue using the domain name, you can log on to the Alibaba Cloud CDN console to add the domain name to Alibaba Cloud CDN again.
  • Domain name disabling: For more information, see Rules for disabling accelerated domain names.
Origin server
  • Address length: The address of an origin server cannot exceed 67 characters in length.
  • Maximum number of origin servers: You can set at most 20 origin server addresses for each accelerated domain name.
  • OSS Domain Name
    • If you use an Object Storage Service (OSS) bucket as the origin server, you can enter the public endpoint of the OSS bucket, for example, ***.oss-cn-hangzhou.aliyundoc.com. Internal endpoints of OSS buckets are not supported.
    • To view the public endpoint of an OSS bucket, log on to the OSS console. You can also select the endpoint of an OSS bucket that belongs to the current Alibaba Cloud account from the Domain Name drop-down list.
  • IP: Enter the public IP addresses of one or more servers. Public IP addresses of Alibaba Cloud Elastic Compute Service (ECS) instances do not need to be reviewed.
  • Site Domain: Enter the domain names of one or more origin servers.
    Note
    • The origin domain name must be different from the accelerated domain name. If the origin domain name is the same as the accelerated domain name, a DNS resolution loop occurs, and requests cannot be redirected to the origin server.
    • The domain name must be in lowercase letters.
    • If the domain name contains Chinese characters such as 阿里云.网址, you must apply for an ICP number for the domain name in Chinese characters, and use the tool Punycode to convert the domain name to English letters, such as xn--fiq****.xn--eq****. Then, you can specify it as the domain name to be accelerated.
  • Function Compute Domain: Enter a Function Compute domain name that belongs to the current Alibaba Cloud account. You must set the Region and Domain Name parameters for the Function Compute domain name. For more information, see Configure a custom domain name.
CNAME CNAMEs that are assigned by Alibaba Cloud CDN, Dynamic Route for CDN (DCDN), ApsaraVideo Live, ApsaraVideo VOD, or Secure CDN (SCDN) are used only for domain name resolution. If Alibaba Cloud discovers that your CNAME is used for malicious activities, Alibaba Cloud reserves the right to close your Alibaba Cloud account and remove the domain names.
Service quota
  • Accelerated domain name

    Each Alibaba Cloud account can add at most 50 domain names to Alibaba Cloud CDN. If the average daily peak bandwidth value exceeds 50 Mbit/s and your workloads are protected, you can submit a ticket to add more domain names to Alibaba Cloud CDN.

  • Cache refresh
    • URL refresh: 2,000 URLs per day for each Alibaba Cloud account.
    • Directory refresh: 100 directories per day for each Alibaba Cloud account.

    If the daily peak bandwidth value of your workloads exceeds 200 Mbit/s, you can submit a ticket to increase the upper limit. Alibaba Cloud will review your application and then increase the quota accordingly.

  • File prefetch

    You can prefetch files only by using URLs. Each Alibaba Cloud account can submit at most 500 URLs per day.

    If the daily peak bandwidth value of your workloads exceeds 500 Mbit/s, you can submit a ticket to increase the upper limit. Alibaba Cloud will review your application and then increase the quota accordingly.

Content moderation

Alibaba Cloud reviews the content of all accelerated domain names. Domain names that cannot be accelerated by Alibaba Cloud CDN include but are not limited to:

  • Websites whose content is inaccessible or does not provide valid information
  • Servers that host pirated games
  • Websites that provide multiplayer role-playing games and card games
  • Websites that provide downloads of pirated software
  • Websites that run peer-to-peer (P2P) lending
  • Lottery websites
  • Websites of unlicensed hospitals and pharmaceuticals
  • Websites that contain pornography, drugs, and gambling content
Note
  • You are legally responsible for the content hosted on your accelerated domain name. Alibaba Cloud CDN regularly reviews the content of accelerated domain names. If illicit content is detected from a domain name, Alibaba Cloud CDN immediately disables or blocks the domain name. If the violation is severe, Alibaba Cloud CDN may even permanently block all domain names that belong to the Alibaba Cloud account.
  • If you add a wildcard domain name, for example, *.example.com, to Alibaba Cloud CDN and a specific domain name, for example, a.example.com, that matches the wildcard domain name contains illicit content, Alibaba Cloud CDN disables the wildcard domain name *.example.com.
  • If a domain name fails the review, you can check the reason for rejection on the Domain Names page in the Alibaba Cloud CDN console. Then, you can modify the content based on the rejection details and submit the domain name for review again.
Back-to-origin routing
  • An HTTP request header cannot exceed 300 bytes.
  • Timeout period

    By default, the timeout period for back-to-origin requests that are transmitted over TCP is 10 seconds. The timeout period for back-to-origin requests that are transmitted over HTTP is 30 seconds.

  • Response header

    If an origin server does not respond to Content-Type, Alibaba Cloud CDN automatically adds Content-Type:application/octet-stream.

  • Automatic conversion from HEAD to GET for back-to-origin requests

    By default, HEAD requests are sent to CDN edge nodes before the requests are redirected to origin servers. In this case, HEAD requests are converted to GET requests. If you do not want to convert HEAD requests to GET requests, you can navigate to the Custom Request Header tab in the Alibaba Cloud CDN console, and configure custom HTTP headers for back-to-origin requests. The following table describes the parameters of custom HTTP headers. For more information, see Configure an HTTP header for back-to-origin requests.

    Parameter Custom header
    Custom Parameters Ali-Swift-Fwd-Head
    Value on
Bandwidth throttling Based on the Alibaba Cloud International Website Product Terms of Service, if the metering method of your domain name is pay-by-data-transfer or pay-by-bandwidth and the peak bandwidth value reaches 10 Gbit/s within 1 minute, Alibaba Cloud enables bandwidth throttling for the domain name. Bandwidth throttling protects your domain name from attacks and prevents unexpected high bills. If you want to disable bandwidth throttling, you can contact Alibaba Cloud customer service or submit ticket.
File
  • File cache
    • If the request to a file that is larger than 100 MB is a cache miss, and the origin server returns a no-cache response header, Alibaba Cloud CDN closes the connection after the amount of data transmitted from the origin server reaches 100 MB.
    • If the origin server returns a response header whose Cache-Control directive allows the response to be cached, CDN edge nodes can cache files that are up to 500 GB in size.
  • Object upload

    You can upload files to origin servers by using Alibaba Cloud CDN. Each file can be up to 300 MB in size.

EdgeScript By default, you can configure only one script for each domain name. If you want to configure more scripts, submit ticket.
Stress testing
If you want to run stress tests on a domain name that is accelerated by Alibaba Cloud CDN, you must submit ticket at least three days in advance. Otherwise, you may experience the following issues:
  • Stress tests on bandwidth may cause bandwidth usage spikes and increase bandwidth costs.
  • Stress tests on the number of queries per second (QPS) may trigger HTTP flood protection rules of Alibaba Cloud CDN and sandbox the domain name.
Length of URLs and HTTP request headers, and total length of URLs and HTTP request headers
HTTP/2:
  • If the default setting of the NGINX directive is http2_max_field_size=32KB, the length of an individual HTTP request header or an individual URL cannot exceed 32 KB. Otherwise, the HTTP 414 status code is returned.
  • If the default setting of the NGINX directive is http2_max_header_size=128KB, the total length of all HTTP request headers and URLs cannot exceed 128 KB. Otherwise, the HTTP 400 status code is returned.

HTTP/1.1: For the large_client_header_buffers directive, number is set to 4 and size is set to 64 KB. In this case, the length of an individual HTTP request header or an individual URL cannot exceed 64 KB. Otherwise, the HTTP 414 status code is returned. The total length of all HTTP request headers and URLs cannot exceed 256 KB. Otherwise, the HTTP 400 status code is returned.

Request method Alibaba Cloud CDN supports the GET, PUT, POST, and HEAD request methods.
Note
  • If you want your website to support DELETE and PATCH requests, use DCDN to enable acceleration for dynamic content delivery.
  • Only POST and PUT requests can carry a request body.
  • By default, Alibaba Cloud CDN converts HEAD requests to GET requests before they are redirected to the origin server. If you want to redirect HEAD requests to the origin server, you can add a custom request header on the Custom Request Header tab in the Alibaba Cloud CDN console. The following table describes how to add a custom request header. For more information, see Configure an HTTP header for back-to-origin requests.
Parameter Custom header
Custom Parameters Ali-Swift-Fwd-Head
Value on
Feature configuration You can add at most 50 configuration records, including the following features: Custom Request Header, Custom Response Headers, URI Rewrite, Parameter Rewrite, and Cache Expiration.
Intelligent and Brotli compression Only files that are not smaller than 1 KB are compressed.
API calls for each user The maximum number of times that each user can call Alibaba Cloud CDN API operations is 1,000 per second. If this upper limit is reached, the following message is returned:
ErrorCode:Throttling
ErrorMessage:Request was denied due to flow control.