Alibaba Cloud CDN. FAQs

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2 Product Strengths Alibaba Cloud CDN Product Strengths Stable and Fast - Advanced distributed system architecture, node reserves:around 500 nodes in China and over 30 abroad - Ample bandwidth and storage resources, a single node supports bandwidth of 40Gbps+ and has a storage capacity of 40 TB PB - Stable and efficient performance indicators, 95%+ hit rate and millisecond-level response times - Mature monitoring and service systems, 24/7 network-wide monitoring, smart scheduling based on service quality Cost Reduction - Elastic resource scalability allows an automatic response to site traffic bursts, without the need of user intervention; automatic response and adjustment; and trend-based QoS traffic control - PayByTraffic billing: lowest price of 0.26 RMB/GB, hourly billing, post payment - PayByBandwidth billing: lowest price of 0.76 RMB/Mbps/Day, daily billing, post payment - Billing for major customers and partners: centralized discounts, simpler and more economical Ease of Use - Self-configuration, including basic configurations, anti-leech configurations, cache policy configurations, and security protection configurations - Open APIs, CDN service activation, basic domain name configurations (add, delete, modify, and query), content push and refreshing, caching rule configurations, and log file downloads Alibaba Cloud Bandwidth and Processing Capacity A single Alibaba Cloud CDN node currently provides a service capacity of 40 Gbps and a total 1

3 processing capacity of over 10 Tbps. How Many Nodes Does Alibaba Cloud CDN Have in China? Does It Have Nodes in Other Countries? Alibaba Cloud CDN has over 50 common nodes and almost 500 storage nodes. These cover China Telecom, China Unicom, China Mobile, China Tietong, CERNET, Great Wall Broadband, and other carriers. A single node provides a service capacity of 40 Gbps. Alibaba Cloud CDN has foreign nodes in Europe, the Americas, East Asia, and Southeast Asia. However, these foreign nodes are not currently available for external service. Learn More In What Scenarios Can CDN Be Used? CDN is applicable to websites with a large volume of traffic, such as online videos, games, pictures, audios, social media, e-commerce, and download sites. CDN caches the content to a node nearer to the user, to enhance the user experience. Therefore, CDN is suitable for use with substantial static resource access volumes, including HTML, JS, CSS, APL, MP3, FLV, JPG, GIF, MP4, and all other static resources. How Can I Use Alibaba Cloud CDN to Optimize Acceleration Performance When used together with other Alibaba Cloud products, it can optimize back-to-source speeds and acceleration performance. - It can work seamlessly with OSS to accelerate website access speeds and effectively lower OSS Internet traffic fees. - It can work with ECS to increase site availability, protect the origin site information on the server, and reduce bandwidth costs. P.S.: CDN can use SLB for origin site address back-tosource. Billing CDN Billing Methods Alibaba Cloud CDN provides two billing methods for users. The PayByTraffic method is charged by the hour and the PayByBandwidth method by the day. The lowest price for PayByTraffic is 0.26 RMB/GB, and 0.76 RMB/Mbps/Day for PayByBandwidth. Learn More About Billing 2

4 How Can I Choose the Right Billing Method? You should select the billing method that helps you save the most based on your actual business needs. - To estimate the bandwidth utilization of your business, you should primarily consider your daily traffic and peak bandwidth. This will allow you to calculate your bandwidth utilization. Users with high bandwidth utilization should choose the PayByBandwidth billing method, while those with low bandwidth utilization should choose PayByTraffic. - General selection guideline: Users with a bandwidth utilization exceeding 30% should choose PayByBandwidth (because of the tiered pricing system, the actual calculation will be slightly different; the results of actual calculation will be used for billing). Note: 1. Bandwidth utilization = actually used traffic/peak bandwidth 2. For 1Mbps bandwidth, 100% utilization for a whole day would generate about GB of traffic Can I Change Billing Methods? The service allows users to switch between the PayByTraffic and PayByBandwidth billing methods. You can directly perform this operation on the CDN console. Note: In a single calendar day, you are allowed to change the billing method only once. Your change will take effect from 00:00 the next day. For example: If you submit a billing method change at 10:00 on June 16th, the requested change will take effect from 00:00 June 17th. If My Account is in Arrears, Will the CDN Service be Suspended? 1. When you fail to pay off the bill for the CDN service, your service will be in arrears. 2. Your service will be suspended when your service fee is overdue by 24 hours. You will be reminded by SMS or to pay the bill promptly within 24 hours of delinquency. Your service will not be affected if you recharge your account within 24 hours. 3. If you fail to do so, your CDN service will be suspended and the CDN billing process also stops. The cache resources you are using will be released, and your configuration information will be retained for 12 months. After the CDN Service Has Been Stopped, Why Does it 3

5 Still Produce Fees? - Because the LocalDNS server has a cache, if the CDN service is deactivated but the cache has not expired, the LocalDNS will still directly hit the CDN node with requests directed at the stopped CDN domain. This will produce a small amount of CDN traffic fees. - Some download software also has LocalDNS caches. In the period before these caches expire, a deactivated CDN domain may produce a small amount of CDN node traffic fees Accelerated Content What File Types Are Supported by CDN? All file formats are currently supported. Different acceleration methods can be used for different files. Currently, there are three primary distribution methods: - Acceleration of images and small files - Acceleration of large file downloads - Acceleration of live streaming media Does CDN Have Size Restrictions for Accelerated Content? There are no restrictions. You can select the appropriate distribution methods for different file sizes - Acceleration of images and small files is recommended if the content to be accelerated is mostly images and Web files - Acceleration of large file downloads is recommended if the content to be accelerated is large files (static files larger than 20 MB) - In case of large video files, acceleration of live streaming media is recommended to accelerate the video on demand and live video services Can the Service Accelerate the Distribution of Dynamic Files? If most of the files under a CDN domain name are dynamic files, we strongly suggest you separate them from the static files. You should use an independent domain name, rather than CDN acceleration, for dynamic files 4

6 Do I Need to Modify the Origin Site to Use CDN? Generally, no. However, we suggest that you first separate static and dynamic resources for better acceleration results. Dynamic and static files should be placed under different domain names and static resources will be accelerated. Does CDN Accelerate the Website's Server or the Domain Name? CDN accelerates the resources under a domain name. If this domain name is set up to accelerate, access to all files under the domain name will go through the CDN Cache Default CDN Cache Rules We support full site acceleration. Please make adjustments based on your own business needs - Default cache policies 5

7 Reminder: If you have dynamic resources that must be set to "No Cache", use a third-level domain name to send the No Cache directory or URL traffic back to the origin site. This will reduce unnecessary traffic fees How Long Can the CDN File Be Cached? - The file cache time refers to the period the file remains in the browser cache. - The CDN cache servers strictly follow the http standard protocol. The specific cache time is determined by the 'Cache-Control' and 'Expires' response headers in the http response header - To find the cache time for html files: Check 'Cache-Control' in the http message header. If "Cache-Control max-age= (seconds)", this indicates the file will be cached for 30 days. In this case, unless the cache is refreshed manually, newly opened browser pages will not have to go back to the source to retrieve the file during the file cache period. Does the Service Support Origin Site Cache-Control Settings? Yes, CDN's cache software follows the http protocol, so the actual cache time is determined by the user's file header (by 'Cache-Control' or 'Expires'). 6

8 Cache Policy Setting Considerations 1. For static files that are not updated frequently, it is suggested that the cache duration be set to one month longer (e.g. image files, application download files). 2. For static files that need to be updated frequently, you can shorten the cache duration based on service conditions (e.g. JS files and CSS files). 3. For dynamic files (e.g.: PHP JSP ASP), the second approach is preferable - Always set "Cache-Control" to "no-cache", "private", or "max-age=0". (Dynamic files are generally login pages with cookie IDs, transaction pages, or pages that must be generated through interaction with a database). CDN will not cache these files, but directly go back to the origin site to get them. - If most of the files under a CDN domain name are dynamic files, we strongly recommend you use an independent domain name without CDN acceleration. Note: After changing the cache configuration rules, the new rules will not take effect immediately, but will automatically become effective upon the expiration of the "original cache configuration". For them to take effect immediately, you must perform a manual refresh. Please note: When refreshing directories, please carefully estimate the back-to-source resource volume to avoid putting too much pressure on the origin site How Can I Ensure Node Cache Data is Updated and Synced in Real Time? CDN is not updated in real time. First, we suggest that you avoid same-name updates. To perform a same-name update, you must submit a refresh request from the console or use the API for manual refresh after the origin site is updated. If you do not manually submit a refresh request, you must wait until the cache file expires before the service will get the new file from the origin site. What Are the Restrictions on Cache Refreshing? Currently, the system supports two methods for refreshing single URLs and directories. A single URL is refreshed in 5 minutes and up to 2,000 URLs can be refreshed each day. A directory is refreshed in about 5 minutes and up to 100 directory refresh operations can be performed each day. What Are the Differences Between Cache Refreshing and Cache Push? What Are the Application Scenarios? - Cache Refreshing: This forces cached resources on distribution nodes to expire. When you initiate another request for the resource, the node must retrieve it from the origin site and 7

9 return it to the distribution node after updating the cache. - Cache Push: This manually pushes origin site resources to edge nodes. When you access the resource, the request can directly hit the cache. This reduces the pressure on the origin site caused by sudden surges in back-to-source traffic. Performance What Is the CDN Cache Hit Rate? This varies with the popularity of user data. The higher a file's traffic, the higher the hit rate. Normally, the hit rate is over 95% How Do You Determine If a Request Hits? Certain data in the return packet can prove that the request hits the CDN cache. You can view the X- Cache information in the Response Headers - 'X-Cache:HIT TCP_MEM_HIT' indicates it hits the cache - 'X-Cache:MISS TCP_MISS' indicates it does not hit the cache What Causes Low Hit Rates? 1. When websites have low access traffic and files are not popular enough, the CDN will receive fewer requests and cannot effectively hit the cache 2. If the cache configuration is inappropriate or the cache time settings for certain files are too short, this may cause frequent CDN node back-to-source 3. The HTTP Header setting may cause the cache to fail. In this case, users must check the origin site's 'Cache-Control' and 'Expires' settings 4. If the origin site has a large number of dynamic resources or mostly non-cacheable content, this can also lead to frequent back-to-source operations Under What Conditions Will CDN Go Back to the Source for Resources? 1. When a user accesses a resource not cached on the node, the resource will be pulled from the source 2. If a file times out on the CDN node, the resource will be pulled from the source 3. Accessing a file that cannot be cached may direct the user back to the source 8

10 How Can Back-to-Source Peak Bandwidth Exceed Network Peak Bandwidth? 1. When enabled, the URL preprocessing function will proactively preprocess origin site resources on the L2 Cache node, leading to an increase in back-to-source traffic, but not network traffic. This causes back-to-source peak bandwidth to exceed network peak bandwidth 2. Because the CDN's level 1 and level 2 caches both support range back-to-source for large files, this effectively lowers the network peak bandwidth. If the user's origin site does not support range back-to-source, back-to-source for large files will increase the back-tosource peak bandwidth so that it exceeds the network peak bandwidth In What Scenarios Will CDN Back-to-Source Fail? 1. When the origin site is overloaded with bandwidth or computing power, normal back-tosource cannot be performed 2. Problematic resources stored on the origin site cannot be accessed through normal backto-source operations 3. In these cases, you can reduce the back-to-source rate by specifying the cache time and upgrading or resizing the origin site Generally, How Long Does It Take to Configure CDN? We guarantee that the period from when the domain name is approved to when acceleration takes effect for each node will be no more than 30 minutes. Domain name information cannot be set for CDN domains in the "Configuring" status. You must wait until configuration is complete and then set the domain name information What is the Use of L2 Nodes? L2 nodes are cache servers located between the user's origin site and the CDN L1 nodes. They can cache CDN L1 back-to-source requests to effectively reduce the access pressure on the user's origin site Functions Does the Service Support HTTPS Acceleration? This function is currently under development and will become available in the future 9

11 Is Pan Domain Name Acceleration Supported? This function will be available soon For Effective CDN Acceleration, How Should I Complete "CNAME Binding" Resolution Configuration? For details, see the CNAME Binding Tutorial What Is the Difference Between "Deactivating" and "Deleting" CDN Domains? - After a CDN domain is "deactivated", its information will be retained and the system will automatically perform back-to-source processing for requests to the CDN domain - After a CDN domain is "deleted", all its records will be deleted. If you only need to temporarily suspend the use of the CDN domain, we recommend using "Deactivate" - To delete a CDN domain from the console, make sure it is already "deactivated" Note: Before "deactivating" and "deleting" a CDN domain, we strongly suggest you restore the domain name A records at the DNS provider to ensure the site remains accessible What Types of Resource Monitoring Does CDN Provide? - Traffic statistics: Monitors the operations of one or more domain names and counts realtime traffic and bandwidth by domain name and time, including network traffic and back-tosource traffic statistics - Request hit rate: The probability of the requests in a certain time interval hitting the cache, i.e. the proportion of all user requests that result in the cache node providing service to end users - Bytes hit rate: The probability that request bytes in a certain time interval hit the cache (bytes = number of requests x traffic). The bytes hit rate directly reflects the back-to-source traffic - Access QPS: qps= total access requests in the time interval/time interval - HTTP CODE: The proportions of http codes (e.g. 200, 304, 404, 500) returned in a time interval - PV: The number of times resource files under the current domain name are accessed in a given time period - UV: The number of unique IP addresses that request resources under the current domain name in a given time period *Regional User Distribution: Analyzes the proportional traffic of users by region - Carrier Shares: Analyzes the proportional traffic of users by carrier 10

12 - File Response Shares: Analyzes the files of different sizes as a share of all responses to users by the day - URL Access Statistics: Ranks the top 100 URLs by access traffic - Page Reference URL Statistics: Ranks the top 100 accelerated pages by access traffic (by referencing URL resources) - CC Monitoring: Shows the peak attack bandwidth and number of attack accesses (codeilist) in a given time interval. The attack information includes attacker IPs and targeted URLs - WAF Monitoring: The peak bandwidths and number of accesses by different WAF attacks in a given time interval. The information includes attackers' IP addresses, attack times, attack URLs, attack types, and processing results Note: The default regions are the regions where the user has purchased nodes. The default domain names are all the domain names for this user Fault Detection If My CDN Domain Cannot be Accessed or the Access Speed Is Slow, How Can I Locate the Fault? 1. Test to see if your website can be accessed 2. Please provide the following test results in the area of unusual access: - Visit " - Ping your CDN domain - Perform "tracert -d" on your CDN domain To learn more, see Fault Locating Methods Submit the test results in a ticket and our customer service team will locate the fault. What Common Faults Do You Encounter When Using CDN? - Local network exceptions - CDN node exceptions - Incorrect cache configurations - Origin site exceptions - Origin site cluster exceptions 11

13 The First Time Data Are Pulled From the Source When Using CDN, Will the Process Be Slow? This process may take longer time than direct back-to-source operations because the cache will not have the data at first. To retrieve data from the source, you must pass through two network layers, the CDN edge layer and intermediate layer. Suggestion: Use the cache's preprocessing interface for resource cache node preprocessing. This will reduce the pressure on the origin site and increase access speeds for the site's resources. To learn more, see Cache Preprocessing Interface How Can I Resolve Excessive Loads on a Single CDN Node? CDN uses monitoring measures to intelligently call adjacent node resources to share excessive loads, so as to ensure effective acceleration. When I Access CDN Accelerated Resources, a 403 Status Code Is Returned When you encounter this problem, see Troubleshooting] Access to CDN Accelerated Resources Returns 403 Status Code403 12