Please do not rely on .com or any domain likely to be seized by a government outside of the jurisdiction in which an exchange actually operates.  For instance, if you use peatio.com, you should expect to needlessly be part of a bulk domain seizure by the US government.  All of your subexchanges are likely to be pulled offline at some point.  The USG does not typically respect other countries' sovereignty where doing so would diminish its own.

Just as importantly, many of your prospective customers will worry that your exchange may go offline, which may send them elsewhere.

If you still prefer the marketability of .com, there is a workaround you may favor:  for anyone going to xy.peatio.com, immediately redirect them to a true .xy domain or to an offshore top-level domain you can trust ("xy.peatio.ok"), where .xy represents each country.

The redirections must be visible so that your customers will always know the true URL, so that when your .com is pulled, they know what to do.

The redirections should properly support https:// or they will encourage man-in-the-middle attacks.  (For that matter, anyone going to the http:// version of any of your sites should simply be told to try again with https://.  It is always insecure to passively redirect non-SSL to SSL connections.  Most sites violate this critical rule.)