Tengxun Cloud CDN Accelerates Deep Configuration and Traffic Package Anomaly Troubleshooting: Practical Optimization Guide
In the cloud native era, CDN is no longer just an "accelerator" for static resources, but also the first line of defense for website security, bandwidth saving and performance optimization. However, many developers often face two problems after accessing Tencent Cloud CDN:
First, the acceleration effect is not obvious, and second, the consumption speed of traffic packets is much faster than expected.
There is usually only one source of these problems:
Return source frequency is too high.
Part I: The underlying logic and billing model of CDN acceleration
To solve the problem, we must first understand how the flow runs.
1. What is Back Source?
When a user requests a file (e. g.
logo.png
), if the CDN edge node does not have a cache for this file, it must go to your origin server (CVM or COS) across the public network to grab it. This process is called
Back to source
。
2. Billing trap: two-way billing
Many people mistakenly think that everything will be fine if they buy a CDN traffic package. In fact, CDN operation involves two expenses:
CDN downlink traffic: the traffic sent by the node to the user (deducted by CDN traffic package).
Origin outbound traffic: the downstream traffic generated by the origin server when the node is fetched back to the origin (charged by CVM or COS). Conclusion: The higher the return rate, the faster you will not only deduct the CDN fee, but also deduct an extra sum of money from the source station.
Part II: Four steps for troubleshooting abnormal consumption of traffic packets
If you find that traffic packets bottomed out overnight, please check in the following order:
Step 1: Analyze the monitoring chart
Enter Tengxun Cloud CDN console to view "Back-to-Source Traffic"
and
"Edge flow" contrast.
Unusual behavior: edge traffic (user access) is very small, but back-to-source traffic is very large.
Judgment: Cache configuration fails, CDN becomes transparent forwarding, and does not play a caching role at all.
Step 2: Check the cache expiration configuration
This is the most common cause. By default, if your server does not return
Cache-Control
Head, Tencent Cloud may adopt a conservative strategy or even not cache.
Check whether the "full site 0 second cache" or short-acting cache (such as 5 minutes) is configured.
Step 3: Check malicious brush traffic
Check the IP source in the Traffic Ranking.
Feature: An abnormal IP initiates hundreds of thousands of requests in a short period of time.
Solution: Enable IP access frequency limit or WAF protection.
Step 4: Confirm billing mode
Make sure you turn on "Billing by Traffic" or "Billing by Peak Bandwidth". The traffic package can only offset the downstream traffic in the "Pay by Traffic" mode.
Part 3: Depth strategy-how to limit the frequency of return to the source?
Reducing the frequency of return to the source will not only keep your wallet, but also greatly improve the loading speed of the first screen.
1. Optimize cache expiration rules (hierarchical configuration)
Don't treat all documents the same. The following strategies are recommended:
Static long-term resources (images, JS, CSS, fonts): slow
Save for 30 days. These files usually have a version number suffix (such as main.v1.2.js), and the contents of the file never change.
Home/Dynamic Pages (HTML): Cache for 5-10 minutes. Use Max-age with stale-while-revalidate mechanisms.
Infrequently Changed Directories: Set a high-priority long cache for the/static/path.
2. Open the "shard back to the source" (Range Request)
For large files (videos, installation packages), be sure to open
Slice back-to-source
。
Principle: When the user only watches the first 10 seconds of the video, CDN only goes to the source station to fetch the first few hundred KB, instead of pulling back the entire 1G video. This can instantly save more than 90% of the back-to-source bandwidth.
3. Ignore parameter cache (Query String Modification)
Many ad statistics or front-end frameworks add random parameters to the URL (e. g.
a.jpg?v=123
).
Configuration suggestion: Turn on "Ignore Parameter Cache" in the Tencent Cloud console ". Otherwise, every different v = xxx will be treated as a new file by the CDN, resulting in a crazy back-to-origin.
4. Cooperate with Tengxun Cloud COS Object Storage
If your source station is CVM (cloud server), it is recommended to migrate static resources such as pictures
COS (Object Storage)
。
Advantages: Tengxun Cloud CDN accesses COS in the same region through intranet, and has exclusive back-to-source authentication optimization. The stability and cost are far better than CVM mount disks.
Part 4: Advanced Techniques-Collaborative Optimization Using Browser Caching
CDN cache does not mean that users do not consume traffic. The real money-saving master will configure
Browser Cache
。
In the "node cache expiration configuration" of the tengxun cloud console, the "browser cache direct setting" can be turned on synchronously ".
Logic: CDN tells the user's browser: "You have saved this map, don't ask me again for 3 days."
Effect: During the second access, the user directly reads the local memory/hard disk, and the CDN traffic consumption is 0.
Part V: Common Error Reporting and Emergency Plan
Problem 1: Caching is configured but does not take effect
Troubleshooting: Check whether the origin station returns Cache-Control: no-cache or private. Tengxunyun CDN respects the settings of the source station by default. If the source station says not to cache, CDN will not cache.
Solution: Configure Force Cache on the CDN side to override the no-cache setting of the origin site.
Question 2: After refreshing the URL, the old content is still there.
Solution: Use Path Refresh instead of URL Refresh ". If the entire version is updated, it is recommended to change the file name or directory name directly.
Problem 3: 403 error in back-to-source
Solution: Check whether back-to-origin authorization for private buckets is enabled ". If COS is private, the CDN must have access authorization to pull data.
Summary: CDN Optimization's "Money Saving Law"
Can cache as long as possible cache: static files in days.
Filter useless parameters: enable ignore parameters and merge cache hits.
Large files must be split: a necessary fee reduction scheme for videos and installation packages.
Normalization of monitoring: set traffic alarms to prevent bankruptcy caused by hacker attacks (brush traffic).
Through the above in-depth optimization, you can not only greatly reduce the back-to-source frequency of Tencent Cloud CDN, but also ensure that every penny of traffic packets are spent on real business growth, rather than unnecessary invalid requests.
