Apache的ServerAlias的作用

今天在php的集成环境laragon上添加了一个虚拟主机，域名为：whathell.com

突然想在前面加个www.

一种做法是在auto.whathell.com文件中添加如下内容：

<VirtualHost *:8090>
DocumentRoot "C:/mysoft/laragon/www/whathell/"
ServerName www.whathell.com
ServerAlias *.whathell.com
<Directory "C:/mysoft/laragon/www/whathell/">
AllowOverride All
Require all granted
</Directory>
</VirtualHost>

虽然可以实现，但又对ServerAlias不解，百度一下发现这个指令是当前虚拟主机的别名，遂

<VirtualHost *:8090>
DocumentRoot "C:/mysoft/laragon/www/whathell/"
ServerName whathell.com
ServerAlias *.whathell.com www.whathell.com
<Directory "C:/mysoft/laragon/www/whathell/">
AllowOverride All
Require all granted
</Directory>
</VirtualHost>

重启apache，发现还是启动不了，遂在网上找到一段话：

Many servers want to be accessible by more than one name. This is possible with the ServerAlias directive, placed inside the <VirtualHost> section. For example in the first <VirtualHost>block above, the ServerAlias directive indicates that the listed names are other names which people can use to see that same web site:

ServerAlias domain.tld *.domain.tld

then requests for all hosts in the domain.tld domain will be served by the www.domain.tld virtual host. The wildcard characters * and ? can be used to match names. Of course, you can't just make up names and place them in ServerName or ServerAlias. You must first have your DNS server properly configured to map those names to an IP address associated with your server.

说domain.tld不能直接访问到网站，需要DNS配置该别名的映射到当前IP，由于是在本地，遂在host文件加上www.whathell.com，然后进浏览器访问，成功了。