You can point one or more registered domain names to the same physical
website, by using the domain name forwarding. This allows automatic
redirection of visitors from the URL they specify in a browser to a site
with a different URL. For example, visitors of the
site www.example.com can be redirected to www.somedomain.tld.
There are two types of forwarding in Plesk: the standard and frame
forwarding.

Standard Forwarding

With the Standard forwarding, users who have been redirected to
another URL can see the destination URL in the browser address bar.

Depending on how long you intend to use the redirection, you can select
the type of redirection – Moved permanently (code 301) or Moved
temporarily (code 302). These are HTTP response codes which Plesk sends
to browsers to perform the redirection. From visitors’ point of view,
the response code does not matter: in both cases they will be simply
redirected to the destination URL. For search engines, the code defines
how they should treat the redirected site and affects search engine
rankings.

• Moved permanently (code 301).

  Use this redirection type if you want to keep search engine
  rankings of your site after moving it permanently to another
  address.

  For example, if example1.com has been moved permanently to the
  domain example2.com, the rankings will not be split between
  example1.com and example2.com – search engine crawlers will
  treat them as a single website.

• Moved temporarily (code 302).

  Use this redirection type when the destination domain is used
  temporarily, for example, when you are testing a new version of your
  site with real visitors while keeping the old version intact. If you
  set this redirection for a newly created destination domain, this
  domain will not be indexed by search engines.

Frame Forwarding

With the Frame forwarding, when visitors are redirected to another
site, the address bar of their browsers continues to show the source
URL. Thus, visitors remain unaware of the redirection. This is called
frame forwarding as the index page of the source site contains a frame
with the destination site.