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The discussion of domains and subdomains is the most helpful thing I have found =[edit]

Putting in extra citations would not help; requesting them is simply calling in to question the validity of what is being said, but I think it does a great job of reflecting the discussion below. Perhaps a discussion of "nominal" use of subdomains would make a good start, which is flagged as being nominal and therefore not always true, followed by a discussion of how the providers muck it up with examples? — Preceding unsigned comment added by (talk) 11:13, 5 December 2016 (UTC)

Discussion of "vanity domain"[edit]

Would recommend that the discussion of alternate uses of "vanity domain" be moved into a separate article to avoid confusion.

I feel this page is absolutely in error to include the negative stuff about vanity domains and its definitions. Has nothing of value in telling us what a subdomain is. My subdomains don't fit those definitions, e.g. wiki.*, ftp.*, map.*, www.*

Motivations have nothing significant to do with what functionality is obtained with subdomains. The section on subdomain shortening services should be removed, it has nothing to do with defining subdomains and appears to be more misguided negative discussion about vanity domains and their affects. An article on URL substitution might house it.

The root cause is the fact that somebody made vanity domain into a redirect to this article, which then necessitates that some mention of its alternate meanings be included. Maybe it should be separated out. *Dan T.* 17:56, 25 November 2006 (UTC)
Done. I've added some content; check it over kthx. EdC 19:13, 4 December 2006 (UTC)
I have added "Vanity_domain" to the See Also list. I think the corresponding content in the main article can be deleted but I am not sure ho to do that.

Sam Tomato (talk) 15:24, 25 November 2011 (UTC)

Broken Link in External Links Section[edit]

The Link Domain Names - Implementation and Specification in the External Links section is broken.

Regards, Siddhesh

Fixed to point to the IETF RFC server. 18:03, 9 August 2006 (UTC)

Validity of information in question[edit]

Real simple,

www = subdomain or third level domain
yahoo = domain name
com = top level domain or TLD

This article is inaccurate and is in need of a rewrite.

Yes, and all are subdomains of of their parent domain. DNS is hierarchical, and the term expresses a relation within that hierarchy. Note that your three-level scheme doesn't apply to gSLD-allocated names. –EdC 00:34, 15 July 2007 (UTC)

This is not really encyclopidic, and it is poorly written. But with my busy schedual I do not have time to edit everything.

Evidently you don't have time to correctly spell your unattributed contributions either. EdC 01:58, 1 December 2007 (UTC)
This is completely incorrect. All of the above except for "." are subdomains. ".com." is a subdomain of ".", "" is a subdomain of ".com.", and "" could be a subdomain of "" IF there are NS records delegating it to some nameserver(s), which there aren't, so it isn't. Kelt65 (talk) 20:09, 7 July 2016 (UTC)

This article is misleading[edit]

A subdomain is not something like That's a Hostname. A case in which would be a subdomain is if you had hostname records within it, like www (, printers ( and so on. The may also be an A record, which is called the domain A record, but that's different. People keep calling things subdomains when they aren't really and its confusing to people who know. This article only furthers that confusion by using examples like being a subdomain. It is not, thats a hostname. So I'd like to get a consensus here before changing the article. -- Suso 19:19, 30 November 2007 (UTC)

Well, this article is in much need of references. That said, all the RFCs (RFC 1034, RFC 1035, etc.) support the articles discussions about what is and is not a subdomain. In the last paragraph of RFC 1034 section 3.1. "Name space specifications and terminology", it gives a fairly clear explanation of a subdomain, which matches this article. As another example, RFC 1035 section 2.3.1 gives the ANBF for a subdomain which matches this article's usage. Domains such as indeed also subdomains. Having A records is not what makes something a domain. Can you please give citations from the DNS RFCs that contradict what this article says? Wrs1864 21:03, 30 November 2007 (UTC)
What Wrs1864 said. is clearly a subdomain, because it is a domain name identifying a domain, and is not the root. Assuming it has an A (or AAAA) record, it is also a hostname, but it is not required to be. Please read the relevant RFCs before setting yourself up as an expert. EdC 01:56, 1 December 2007 (UTC)
What on earth? "" can be either a FQDN of a host or a domain name. It is not all at "clearly a subdomain". The only thing certain you may infer is that "" is a domain. There is no difference between a subdomain and a domain unless the domain is the top level root domain, ".". All domains are subdomains of the root. All subdomains are also domains. A domain, or a subdomain, must have a delegation (NS records) for it to be a "domain", otherwise, it is something else. It is true that webhosting companies have polluted the language here by calling host records "subdomains". The article is correct as it stands today. Kelt65 (talk) 20:18, 7 July 2016 (UTC)

false information[edit]

The way this article reads, it seems as though if a website goes down, the websites that are hosted on it also go down, however there are 2 notable exceptions to this, Doom WAD Station and are currently down websites. However some and (as well as [[ and are still up, yet their websites are 404. —Preceding unsigned comment added by (talk) 13:26, 1 June 2008 (UTC)

From my reading of the article, it doesn't appear to address such issues at all. In any case, there is a distinction between fundamental Internet services such as DNS and application-level services such as HTTP; a site's DNS can well be responding fine even when some of its HTTP services are unavailable. EdC (talk) 18:10, 1 June 2008 (UTC)

www. ???[edit]

Can someone please tell me how the www. subdomain works(if it even is a subdomain) is it right to imagin the "subdomain tree" like this:


         |         |

(sorry for my bad looking ASCII tree drawing :P)

or is the www. subdomain something more than a regular subdomain?--Ismetteren (talk) 17:11, 17 May 2009 (UTC)

In your example above, is considered a subdomain as far as this article and DNS theory goes. For almost every domain out there, www will have an A record associated with it that points to the IP address of a web server (or a CNAME that points to a domain name that resolves to a webserver). One thing to remember is that, although most websites are accessed by going to www.somedomain.sometld , this is only due to a generally accepted naming convention and is not strictly enforced by DNS itself. So there is no special external www service, container, or ruleset. Each DNS zone file can define www as whatever it wants, or as nothing at all... I can make go to a FTP service or a mail server if I want to (it just wouldn't make a lot of sense), or I can leave it completely undefined and use instead as the URL for loading a website within -- Dgmackay (talk) 23:28, 9 June 2009 (UTC)

Perhaps it makes more sense as a tree, which is what the DNS is -
 .                            # root domain
 └── com                      # com domain/tld
     └── example              # domain, subdomain of .com
         ├── sub              # domain, subdomain of
         │   └── www          # indeterminate, could be host name or domain
         └── www              # indeterminate, could be host name or domain

We know "" is indeed a domain as the existence of the record "" requires it.

Kelt65 (talk) 20:27, 7 July 2016 (UTC)

Name for a directory that acts like a subdomain?[edit]

If you create a directory that contains a html file named "index" it will act like a subdomain or separate site (e.g. typing into your browser will automatically open the index file in the directory lojong of the site Obviously adding the index file makes the directory lojong something different than a regular directory -- does anyone know what such a directory is called?