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If I own a domain do I own all of its sub domains?

For example if I purchase example.com, do I automatically own mail.example.com, blog.example.com, etc?

If I do not own the sub domains, can anyone buy mail.example.com if I own example.com? Do I have a right of first sale if someone tries to buy one of my sub domains?

Finally, do the answers to the above questions apply to all domains in all TLDs, like .org, .net, .ca, .name, etc?

Thank you.

EDIT: According to the .name agreement registration restrictions at

http://www.icann.org/en/about/agreements/registries/name/appendix-11-25mar11-en.htm

an individual can register a .name domain only if the domain matches the eligibility requirements. There are several eligibility requirements, one of which is that a .name domain must be the real name or identifier of an individual. So, for example, firstname.lastname.name and firstnamelastname.name are both valid. However, lastname.name is not valid because it does not identify an individual. If I registered lastname.name, someone else could mount a challenge based on the eligibility requirements and register otherfirstname.lastname.name. So I do not in fact control the sub domains.

Am I reading that right? Are there similar restrictions on ownership of subdomains in other TLDs?

Matthew Fournier
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Yes, you own and control the entire namespace below the domain you purchase, because DNS is hierarchical. Creating mail.example.com and blog.example.com is just a matter of adding entries to the DNS zone that you control.

Since you asked about the name. domain, I'll address that specifically: You cited its eligibility requirements and have confused this with domain control. If you aren't eligible to have the domain to begin with, then the point is moot.

In the case of name. and a few other top level domains, it may be valid to register a second-level, third-level or a fourth-level name, depending on that domain's individual eligibility requirements. For instance, us. allows second-level registrations to anyone, but for historical reasons, there exist many second-level registrations corresponding to U.S. states which are registered to state government agencies, and where the third or fourth level is further delegated to agencies within those states.

Michael Hampton
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  • You are the root for that domain so anything that extends upward (leftwards) belongs to you. <-- .example.com. – Fiasco Labs Sep 08 '13 at 18:16
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    This is true when the word "own" is used correctly -- +1 -- but I think it's worth mentioning that there are some crappy webhosts that will happily give other people subdomains of your domain, because just because you *think* of a domain as yours doesn't mean you actually "own" it. (This has had serious security implications in some cases.) So it's worth checking. – ruakh Sep 08 '13 at 19:16
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    @ruakh Do you have an examples of companies which have done this, because I would think that'd be against IANA rules. – Andy Sep 08 '13 at 20:25
  • @ruakh afraid.org was doing this for quite a while, and might still be. – Michael Hampton Sep 08 '13 at 21:53
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    @MichaelHampton: Thanks! It turns out that yes, that's the one I'd seen: http://serverfault.com/a/427300/100777 – ruakh Sep 08 '13 at 22:01
  • Thanks for the answer! However I did some more research and I'm not sure if this is true for all TLDs. Please see my edit. – Matthew Fournier Sep 09 '13 at 00:46
  • @ruakh to be pedantic when the word own is used correctly, you have the right to resell. So if you buy example.com, then I can buy (if I make an offer that you accept) good.example.com. At that point, you would not own and control the entire namespace. – emory Sep 09 '13 at 00:50
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    @emory: `At that point, you would not own and control the entire namespace` Not quite correct. Since you're not a domain name registrar, you are still in control of the entire namespace; your allowing other people to use your subdomains is a private matter and is done under private terms. If you buy a subdomain from a non-registrar, you should not assume that you also own the subsubdomains. – Lie Ryan Sep 09 '13 at 02:30
  • Thank you very much! I haven't gone through the entire purchase process yet, but some registrars appear to allow you to purchase lastname.name, which gives the impression that you own it. Hence my confusion. But as you say, the standard does not allow ownership of that domain, no matter what the registrar says. Thanks for your help. I'm marking this answer as correct. – Matthew Fournier Sep 09 '13 at 12:01
  • @MatthewFournier In the case of `name`, it wouldn't be valid to just purchase `lastname.name`. Any registrar doing this is doing something seriously wrong. But a purchase of `firstname.lastname.name` would be valid. – Michael Hampton Sep 09 '13 at 12:30
  • wrong -- just owning `com` does not guarantee you own `google.com`. Please explain – 6005 Dec 10 '17 at 04:34
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    @6005 You can't own `com.` so your comment doesn't really make any sense. What are you actually trying to ask? Please try rephrasing your question. – Michael Hampton Dec 10 '17 at 22:41
  • @MichaelHampton is it legal to user popular names as subdomains? Like aws.example.com, gcp.example.com?? – Sami Haroon Jan 28 '20 at 07:58
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    @SamiHK That's a good question to ask your lawyer. – Michael Hampton Jan 28 '20 at 18:30
  • Thanks for this explanation – chidimo Sep 09 '20 at 11:48
  • "In the case of name, it wouldn't be valid to just purchase lastname.name. " Yes, when `.name` started only 3rd level domain names were possible; this has been lifted then and now .name is like any other gTLDs and you can register at second level, while all previous domains at third level continue to exist. So if `firstname.lastname.name` was already registered, you can't register today `lastname.name` and the opposite as well. – Patrick Mevzek Jun 21 '21 at 06:20