What Is The Wildcard Of The Dns? for changing the setting of my domain

[whistle 0]

I want to learn about how to modify DNS setting by using PHP. Someone tell me that the DNS server must support wildcard. What is it? Where can I find the information or the example?

[whistle 0]

I considered that wildcard is used for modified or update dns. I am wrong. That wildcard is an A name specified by "*" for pointing to a host ip. Of course the host ip should be where the website hosted.But how do it work? Please correct me if I am wrong. I guess that wildcard is a catch all function. As the email, when you set a catch all email account for you domain, every mail sent to the domain will forward a copy to the catch all email account. The dns wildcard seems so, every query will forward to the ip where the website hosted. Therefore the website will response the query according to the information of the query.For example, this could be used for url forwarding. When the query arrives to the website, the website can forward the query to a predefined url according the url of the query. The url could be a subdomain. Maybe it can be a url with a subdomain, I am not sure.Of course, it can also support multi-domain. For the purpose, the httpd must be modified for a plurality of domains. I don't know how to do it, I think that is called virtual hosts.I longer for more details about the wildcard in dns. Hope some experts can share your knowledge here.