CNAME记录中的*是否优先于显式子域？

Question

我在我的域上定义了一组子域,如下所示:

CNAME sub1.example.com -> sub1.herokuapp.com
CNAME sub2.example.com -> sub2.appspot.com
CNAME www.example.com -> example.herokuapp.com

现在我想补充CNAME *.example.com -> example.herokuapp.com一下,抓住那些投入太多WWW或输入其他缺失子域名的人.但是,*优先于明确定义的子域还是子域继续按预期工作？

如果它有所作为,我正在使用Route53.

Answer 1

通配符仅匹配区域中未另行定义的记录.

参见RFC 1912,它MX在这里提到了记录,但同样适用于CNAMEs:

2.7 Wildcard records

Wildcard MXs are useful mostly for non IP-connected sites.  A common
mistake is thinking that a wildcard MX for a zone will apply to all
hosts in the zone.  A wildcard MX will apply only to names in the
zone which aren't listed in the DNS at all.  e.g.,

       podunk.xx.      IN      NS      ns1
                       IN      NS      ns2
       mary            IN      A       1.2.3.4
       *.podunk.xx.    IN      MX      5 sue

Mail for mary.podunk.xx will be sent to itself for delivery.  Only
mail for jane.podunk.xx or any hosts you don't see above will be sent
to the MX.  For most Internet sites, wildcard MX records are not
useful.  You need to put explicit MX records on every host.

Answer 2

不,它没有,定义的子域应该优先于通配符.