Shulou(Shulou.com)06/01 Report--

Two new record types are implemented in bind9: DNAME,IP6 This article describes what DNAME implements.

rfc2672 describes DNAME. rfc's title is "Non-Terminal DNS Name Redirection," which is similar to CNAME, but it does not alias a single name, but an entire domain name. When DNAME is discovered, it doesn't end there, it calculates a new name and resolves it. CNAME is different. When CNAME is found, the job is over.

It's fairly simple to use:

DNAME

The effect is that the entire subtree of the entire owner identifier is mapped to the target domain name. This is to create a mechanism to facilitate easy renaming of domain names when the network is re-planned, both original and newly added domain names.

Let's imagine a situation where a company's website, e.g. a.com, decides to buy company b.com, decides to make a subdomain of a.com for b, and makes b.com a subdomain of a.com, i.e. b.a.com. In other words, in order to keep the original still working and compatible,b.a.com needs to still work during the deployment of b.a.com. At this point, the administrator simply adds a record to the a.com domain:

b DNAME b.com.

When querying, such as www.b.a.com, the resolver receives a DNAME result b.com for b.a.com; the resolver needs to translate the domain name to www.b.com and parse it. In the response, contain a CNAME record for the requested domain name with the value of the domain name replaced with DNAME. This way, resolvers that are not compatible with DNAME will work as usual.

We often run into a problem: there is a domain name that will make the top level of this domain name CNAME, such as domain name a.com, want to do CNAME to b.com, which is usually not allowed (this is an easy mistake to make, cname only allows subdomain name CNAME). This can be done with DNAME.

For example: a.com zone file:

b.com zone file:

Results:

DNSDUN Usage Settings:

DNSDUN is currently the only dns provider that supports the DNAME type.

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