Tell me why we have a cname.

Do the Internet, Cdn have to deal with the CNAME, work also encountered a lot of knowledge about the CNAME, now to do a summary of the CNAME, why to have a CNAME, and the value of the CNAME existence is what, to initiate, purely personal understanding!!!

1, reduce the multi-domain name, multi-server, multi-service operation and maintenance costs. after the domain name cname to the new address, reduce the complexity of the authoritative DNS configuration, changing the configuration of frequent (such as a record, MX record), functional business (intelligent multi-line, CDN distribution) and other cutting separation, after the failure to troubleshoot simple and clear, The problem is who is the problem, and the authoritative DNS update in the global synchronization takes time, so the less the better, the current industry competition, to ensure a good user experience and the high availability of the site is very important.

2, multiple domain names, various services resolved to the same host, Also does not affect the search engine collects. For example, there are multiple domain names (www, mail, News) services to the same public network server, The server external domain name is host.aaaabb.aaaa.aaaa.com.cn (possibly the public network IP corresponds to the server cluster, and the public network IP may change), this is a typical application scenario, by the CNAME of these domain names points to host  

3, solve multi-line and CDN distribution acceleration problem. for multi-line problems, through the CNAME, you can do intelligent DNS on the CNAME, the telecommunications users go to the link of telecommunications, unicom users to go to the link, improve user experience, save the link cost, for CDN distribution acceleration, Most are through the CNAME plus a GSLB (global load Balancing) to achieve, your domain name cname to the CDN manufacturer to your domain name, the rest of the matter will not worry about, of course, you can also self-built CDN, own a GSLB to do dispatch distribution.

4. Solve the problem of performance load under high concurrency. in fact, business separation, CDN distribution has been invisible to solve a part of the load problem, Large web site concurrency is very powerful, in order to resolve the problem, you need to buy paid DNS, resulting in higher costs, and inconvenient maintenance, At this time you can cname to a domain name, set up the CNAME domain name NS for their own DNS, there is a way to directly configure the ForWord, so that the intelligent analytic business pressure on your own DNS, The application scenario is flexible and original aim.

This article is from "Running Linux ..." Blog, be sure to keep this source http://benpaozhe.blog.51cto.com/10239098/1746573

Tell me why we have a cname.