Types of CDN Resources

There are two types of CDN resources: HTTP PULL and HTTP PUSH. Each has its own advantages and disadvantages and each works better with different types of sites.

HTTP PULL Resource:

Sites’ owners put contents in a server and set up DNS CNAME which allows users to visit the webs pages through multiple CDNs directly. It means at first time when a user visits web pages, a CDN will indicate the origin server then pull the file and serve it. In the same time, the CDN server will cache that file until it expires.

The advantage of HTTP PULL is easy to set up. It starts working right after the setting of DNS CNAME is completed.

However in these two scenarios, it will take a bit long to open a web page.
One is when a web page was opened at the first time in the area; the other is when an end user visits it after the cache has expired. End users may notice a difference in between.Therefore, setting the appropriate expiration will help resolve this kind of issues.

HTTP PUSH Resource:

HTTP PUSH works as a secondary server. Sites’ owners need to upload content to a CDN server and then CDN supplier distributes to all individual CDNs, which means the sites’ owners can upload specific content to meet their needs.

The advantage of HTTP PUSH is to keep the traffic of an origin website minimum because content only needs be uploaded when it is new or has been changed.
Also when the peak time of the website comes, the traffic can stay under controlled since the content has been uploaded on the CDNs at off-peak hours in advance.

However, the disadvantage is that end users need to upload content to a CDN server  via FTP every time when the file has changed.

Here are some tips for your choosing:

• HTTP PULL
  It is recommended to use on websites which have more static content with low frequency of file download. Suitable for transfer of small files, end users hardly feel the difference even it is the first time to visit the web page.
• HTTP PUSH
  It is recommended to use on websites which provide more file download services. It is more suitable to transfer big file, such as software installation or file big than 50MB.

CDN related articles, please refer to the below links :

Creating CDN Resources : HTTP PULL Resources :
http://noc.emagineconcept.com/index.php?/DotToGo/Knowledgebase/Article/View/588/44/18-creating-a-http-pull-resource-for-cdn

Creating CDN Resources : HTTP PUSH Resources :
http://noc.emagineconcept.com/index.php?/DotToGo/Knowledgebase/Article/View/713/44/19-creating-a-http-push-resource-for-cdn

For more related articles about CDN, please check our knowledge base :
http://noc.emagineconcept.com/index.php?/DotToGo/Knowledgebase/List/Index/13 

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