- What is the concept and role of a CDN?
- What is CNAME?
- How long does it take to create the CDN domain name?
- Is a record number necessary for activating CDN?
- Do second-level domain names need to be filed?
- How long can CDN serve with record number invalid?
- Can I use the Content Delivery Network if the domain name is redirected?
- If I use Content Delivery Network acceleration with a blob, do I directly use the blob address, rather than the custom domain name? Do I need to apply for filing and, if so, why?
- How do I ensure that content is synchronized with the origin domain after I set up a CDN?
- How do I enter the return-to-source host header?
- How do I change the source station address?
- How do I bind CDN edge nodes?
What is the concept and function of the CDN?
Azure Content Delivery Network adds a new layer of network architecture to the existing Internet by caching the content of websites to the network “edge” nearest to the user. With this new layer, you can obtain the required content from a closer location, which provides a high-bandwidth, low-latency user experience.
What is CNAME?
A CNAME (canonical name) record generally redirects to an alias. For example, if your custom accelerated domain name is www.abc.com, the CDN service domain name provided by website acceleration (after you have configured it) would be www.abc.com.mcchcdn.com. You must have the domain hosting service provider delete the corresponding A record for www.abc.com and add www.abc.com.mcchcdn.com as the CNAME record for the domain name. Then, when you access www.abc.com, you will obtain the IP address record of the accelerated node that was parsed by www.abc.com.mcchcdn.com.
How long does it take to create Content Delivery Network domain name?
The process of checking that the supplied custom domain name and ICP number match and are valid takes no more than one business day to complete. If the details pass the Internet Content Provider (ICP) review, the Content Delivery Network service will be registered within 60 minutes, so that it can be propagated by the network. At the same time, you also need to configure the CNAME mapping details, as indicated by the notifications in the interface, before the cache content can finally be accessed via the custom domain name.
Is a record number necessary for activating Content Delivery Network?
The Ministry of Industry and Information Technology requires a record number for using Content Delivery Network. In terms of the specific ICP filing requirements, the only requirement is that the custom Content Delivery Network acceleration domain name you use has an ICP. There are no requirements for the source station itself, and source stations both inside and outside China are supported.
Do second-level domain names need to be filed?
Second-level domain names do not need to be filed. For example, if sample.com has been filed, images.sample.com does not need to be filed, and it is sufficient to provide the record number for sample.com when you create the Content Delivery Network acceleration node.
How long can Content Delivery Network serve after the record number becomes invalid?
When the record number is expired, you should update it at the Communications Authority themselves. By default, it will be forced to return to source if it is not recorded within 7 days. If the recording period is too long, and you want to use a Content Delivery Network service, you can contact us by issuing a work order.
Can I use the Content Delivery Network if the domain name is redirected?
Yes, but we suggest that you accelerate the domain name following the redirect, because it is not necessary to accelerate domain names before the redirect.
If I use Content Delivery Network acceleration with a blob, do I directly use the blob address, rather than the custom domain name? Do I need to apply for filing and, if so, why?
CDN (Content Delivery Network) is a group of network content caching nodes and is not equivalent to a customer’s origin domain. The caching nodes only incorporate only the content that you have set up for caching, and even this might expire.
The purpose of custom domain names is that they can be given a CNAME so that the source station cache hit is directly returned when source website content is accessed via Content Delivery Network by using the custom domain name. Otherwise, it might be returned to source. This is the principle of Content Delivery Network.
If the custom domain name and the origin domain name were the same, the results would be:
- A back-to-source failure because the acceleration node would be accessed again via DNS instead of the source station when returning to source.
- An access failure because part of the source station content might not be on the acceleration nodes.
The law stipulates that custom domain names are subject to ICP record filing, but there are no requirements for source stations. However, if the second-level domain name for the custom domain name itself has already been filed, it is not necessary to file another application.
How do I ensure that content is synchronized with the origin domain after I set up a CDN?
When you set cache rules, you should set different cache refresh rules for different content. To reduce pressure on the source station, you can set shorter cache times for frequently updated content and longer cache times for content that is not regularly updated.
If the cache refresh period that you set does not expire, but new content is published or some of the content is deleted, you can use the cache refresh features provided by the Content Delivery Network management platform to manually force it to refresh.
[!NOTE] If you want to update only one particular file, we recommend that you use File Refresh to refresh the updated file. Directory Refresh will refresh all the files in the directory. This refresh can take some time to take effect.
How do I enter the return-to-source host header?
When you create the Content Delivery Network in the Azure portal, enter the return-to-source access host header that's accepted by your source station in the origin host header. After you have entered the custom domain, the system automatically fills in a default value based on the origin domain type that you selected. Specifically, your source station is on Azure, the default value is the corresponding source station address. If your source station is not located on Azure, the default value is the custom domain name that you entered.
If your source station is by default unable to use the custom acceleration domain name for access, you will need to configure the return-to-source host header. You should configure it based on your specific situation, but in general you can configure the source station domain name at this time. If the source station has other configurations, those configurations should be followed.
How do I change the source station address?
First, make sure that the new source station is working normally. Then go to the domain name management section in the Azure Content Delivery Network advanced management platform, change the source station address to the new address, and then save the change.
Note: If there are any changes to the real IP of the origin domain, whenever possible, you should remove the old IP after the configuration has taken effect.
How do I bind CDN edge nodes?
After you have successfully created a Content Delivery Network service for your origin domain www.mydomain.com on the Azure CDN platform by using the customized domain name cdn.mydomain.com, you will receive the accelerated domain name cdn.mydomain.com.mcchcdn.com. You can bind the host to perform basic troubleshooting. This is done by using the following procedure:
ping cdn.mydomain.com.mcchcdn.com obtains the IP address of the edge node，for example: a.b.c.d
2. Edit the local host's file, and then add the record a.b.c.d www.domain.com.
Then visit www.domain.com in a browser. If the website appears correctly, then there are no problems with the Content Delivery Network. If you cannot access the website, but the website can be successfully accessed after the IP address in the host file is changed to the IP address of the source station, there is a problem with the Content Delivery Network server.
[!NOTE] In Windows, the path for the hosts file is C:\Windows\System32\drivers\etc\hosts.
In UNIX-like operating systems such as Linux or BSD, the path for the hosts file is /etc/hosts. Administrator privileges are required to edit this file.
For the Azure Blob service and Cloud Services, you will get a 404 error message if you directly access the domain name . In such cases, you can troubleshoot by visiting a valid URI.