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Comment fonctionnent ServerName et ServerAlias ?

ayi

C'est le suivant part of a virtual host config that J'ai besoin de further clarification on:

<VirtualHost *:80>
  # Admin email, Server Name (domain name), and any aliases
  ServerAdmin example@example.com
  ServerName  141.29.495.999
  ServerAlias example.com
...

Ceci est et example config, similaire to what I currently have (Je ne have a domain name at le moment).

<VirtualHost *:80> - Allow le suivant settings for tous HTTP requests made on port 80 to IPs that this server can be contacted on. Par exemple, si le server could be accessed on more than one IP, you could restrict this directive to juste one à la place of both.

ServerName - If le host part of le HTTP request matches this name, alors allow le request. Normally this would be a domain name that maps to an IP, mais dans ce cas le HTTP request host must match this IP.

ServerAlias - Alternate names accepted by le server.

The confusing part for me is, in le ci-dessus scenario, si I set ServerAlias mytestname.com et alors made an HTTP request to mytestname.com, there would have to be a DNS record pointing to le server's IP for this to work? In qui case, is ServerAlias juste basically EXTRA ServerName entries?

Say I had a DNS entry such that foobar.com = 141.29.495.999 mais alors I had ServerName = 141.29.495.999 et ServerAlias was empty, would that mean that bien que foobar.com gets resolved to le right IP, parce que there is no reference to accept foobar.com in ServerName ou ServerAlias?

Or something. Man Je suis confused.

ayi

Think of it like this:

DNS is le phone directory/yellow pages. When someone wants to call votre phone, they can look up votre name et get votre phone number et call that phone. DNS does le même mais for computers - quand someone wants to allez dans www.example.com they ask DNS for le IP address et alors they can contact le computer that has that IP address. That is what resolve means. Resolving an IP address has nothing at tous to do avec Apache; it is strictly a DNS question.

The ServerName et ServerAlias is more like a company's internal phone list. Your webserver is le switchboard; it will accept tous incoming connections to le server. Then le client/caller will tell them what name they're looking for, et it will look in le Apache configuration for how to handle that name.

If le name n'est pas listed as a ServerName/ServerAlias in le apache configuration, apache will toujours give them le premier VirtualHost listed. Or, si il y a no VirtualHost at all, it will give le même content no matter what hostname is given in le request.

ETA: So, step by step for a normal connection:

You type http://www.example.com into votre browser.
Your computer asks its DNS resolver qui IP address it should use quand it wants to talk to www.example.com.
Your computer connects to that IP address, et says that it wants to talk to www.example.com (c'est le Host:header in HTTP).
The webserver looks at its configuration to figure out what to do avec a request for content depuis www.example.com. Any one of le suivant may happen:
www.example.com is listed as a ServerName ou ServerAlias for a VirtualHost - si so, alors it will use le configuration for that VirtualHost to deliver le content.
The server ne have tout VirtualHosts at tous - si so, alors it will use le configuration in its httpd.conf to deliver le content.
The server has VirtualHosts mais www.example.com n'est pas listed in tout of them - si so, le premier Virtualhost in le list will be used to deliver le content.