CNAME记录中的*是否优先于显式子域名？

Question

我有一组这样对我的定义域的子域：

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捉放太多WWWs或类型的其他子域失踪谁乡亲。但*将优先于明确定义的子域名，还是子域名将继续按预期工作？

我使用Route53，如果它有所作为。

Answer 1

通配符只会匹配没有在区域中定义的记录。

见RFC 1912，它提到MX记录在这里，但同样适用于CNAME S：

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，没有定义的子域应该优先于通配符。