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Thread Index [isp-dns] Re: DNS zone!
On Mon, Jan 27, 2003 at 02:19:06PM -0500, Alex Kamantauskas wrote:
| > Is the CNAME practice what is taught in books, courses, etc, or are
| > people just blindly copying from bad examples?
| >
|
| The most effective use of the CNAME is when you have a single IP address
| that has several names associated with it - by changing the canonical
| name you then update all of the aliases.
|
| If you only have one or two names associated with an address, than its
| probably easier in the long run to just use A records - then you won't
| run into the issue of CNAME restrictions (or have to train someone about
| it) and other issues.
If you generate your zone files from other data sources, such as a
customer database, then you don't need any CNAMEs. Just generate
the records you need for each name. But for those who do manually
edit zone files, it would be nice if there was some kind of internal
reference such that the server will internally use the data from
some other name, but answer as if that other data belonged to the
queried name. For example, suppose I call it "USE", then there
could be:
example.com. 86400 IN A 10.20.30.40
86400 IN A 10.20.30.41
86400 IN A 10.20.31.40
86400 IN A 10.20.31.41
86400 IN MX 0 mail.example.com.
86400 IN MX 1 mx.example.com.
mail.example.com. 86400 IN A 10.10.10.25
mx.example.com. 86400 IN A 10.10.25.10
example.net. USE example.com.
example.org. USE example.com.
So if you query example.net then you would get all the same records
as if you queried example.com, even though the server won't need to
load extra copies of those records. This would only work if the
name referenced by the USE "record" is loaded by that server.
--
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| Phil Howard - KA9WGN | Dallas | http://linuxhomepage.com/ |
| phil-nospam@ipal.net | Texas, USA | http://ka9wgn.ham.org/ |
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