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This first paragraph used to look like this:
A fully qualified domain name (or FQDN) is the human-readable name corresponding to the TCP/IP address of a network interface, as found on a computer, router or other networked device. It includes both its host name and its domain name.
I changed it. Here is my reasoning.
The statements contained in the first paragraph are incorrect. A FQDN doesn't have to be human-readable, unless in the sense that it uses human readable characters. A FQDN could be rs3927-8H.as4823.net. Is that human-readable? My point is that it has dual purpose, both human and machine.
Secondly (and more importantly), an FQDN does not correspond to ANYTHING, not by definition. There are multiple resource record types that you can use with domain names. I will point to IN TXT as a valid, but non-TCP/IP address RR as an example of why this is not true.
What i have changed the paragraph to is more correct, and does not mislead the reader into a narrow view of what DNS is capable of.
- Fudoreaper 22:28, July 29, 2005 (UTC)
I am not sure if "canonical name" is the same as and should be directed to "FQDN". I read that if one uses /etc/hosts, the first hostname on the list is considered as the canonical name. So, if the first name is a unqualified name, the canonical name is the unqualified name. It seems canonical is as opposed to aliases, and FQDN is opposed to unqualified name - they are two different concepts. That is, all the canonical and aliased names can be fully qualified, and also can be all unqualified. I read that "canonical name" is defined in RFC103.
- Ming Kin Lai
—Preceding unsigned comment added by 128.195.10.233 ( talk • contribs) 2006-09-27T19:21:35
"Any binary string can be used as the label of any resource record; a common misconception is that names are limited to a subset of ASCII characters." according to RFC1035 sec. 2.3.1, in order to be backward compatible, one should use the "let-dig-hyp" characters only.
- Yuval —Preceding unsigned comment added by 212.235.26.189 ( talk) 09:45, 19 February 2008 (UTC)
I have never heard mention of an 'absolute domain name', which we say is an alternative to 'fully qualified domain name' in the opening paragraph. Can anyone say where they've heard this, or even better, cite a source? — fudoreaper ( talk) 08:27, 18 March 2009 (UTC)
PS: I think the notion of 'ambiguity' requires context, for example, if a host 'myhost' belongs to two domains for which it has, say, different SRV records. Only in this context would the local use of 'myhost' be ambiguous, but outside of these domains, where this context is unavailable, the name is simply incomplete and likely unresolvable. Kbrose ( talk) 17:59, 18 March 2009 (UTC)
Back before I did a rewrite (see here), this article claimed: "Notice that there is a dot at the very end of the domain name, i.e. it ends ".com." and not ".com" — this indicates that the name is an FQDN. For example "myhost.bar.com" could be ambiguous, because it could be the prefix of a longer domain name such as "myhost.bar.com.au", whereas "myhost.bar.com." is a fully qualified domain name." I found this kind of bogus due to the ndot rule, but the whole article stressed the "requirement" that a FQDN must have a dot at the end. I'm not sure how much this is a "common misunderstanding" in the general population, but there was a little more text that addressed the issue. Wrs1864 ( talk) 18:00, 18 March 2009 (UTC)
A full does imply a partial. Is there a partial?
Which are the phrases to describe the distinction, please, between, with www. verus without? Such as [ my examples include en., nothing, then www.. ]:
http://www.wiktionary.org/wiki
[[ hopiakutaPlease do sign your communiqué. ~~ T hank You, DonFphrnqTaub Persina.]] 10:00, 4 September 2009 (UTC)
Please, help?
Anyone home?
[[ hopiakutaPlease do sign your communiqué. ~~ T hank You, DonFphrnqTaub Persina.]] 22:15, 8 September 2009 (UTC)
The third paragraph states that "The FQDN therefore uniquely identifies the device". For this example, this is true, but it is not universally true. The FQDN may refer to a round-robin set of machines or even a name that has no specific machine associated with it; the key is that within the complete domain name system, it points to a specific node within the tree. Corydon76 ( talk) 18:17, 6 November 2009 (UTC)
If there is to be a trailing dot at the end of a sentence, that must be clearly defined by another method than only one dot. Either use two, or use a separate box to display the example; ie.
somehost.example.com.
Was this what was actually meant? - KitchM ( talk) 20:46, 10 November 2009 (UTC)
How about an FQDN example? scope_creep ( talk) 16:01, 23 August 2010 (UTC)
My edit has been reverted by user tbhotch within several seconds (so he/she has not read the RFCs but just disliked the edit). Text of my edit was: It seems that a significant part of this article is PLAIN WRONG. See RFC 1594 (Section 5.2) for Fully Qualified Domain Name (FQDN). This RFC is cited by several other RFCs using the term FQDN. See RFC 1034 and RFC 1035 for absolute domain names (sometimes called complete domain names). The terms FQDN and absolute domain name are NOT synonyms. Maybe someone with Wikipedia formatting skills can add a hint to the article. People rely on Wikipedia but information given in the article is PLAIN WRONG. I am a UNIX admin for nearly 20 years and I do read RFCs (which are the relevant source for internet related things by definition). (I had added some asterisks to my original edit as I do not know how to format Wikipedia articles to emphasize that important information.) — Preceding unsigned comment added by 84.128.50.110 ( talk) 22:45, 30 September 2012 (UTC)
Googling suggests that PQDN is often discussed alongside FQDN, and there is a competent article at FQDN as compared to the totally unsourced dictionary definition at PQDN: it looks as if it would be better to add some description of PQDN to the FQDN article and redirect. Pam D 22:47, 20 May 2014 (UTC)
-- 74.93.100.211 ( talk) 00:25, 18 November 2014 (UTC)
Support PQDN is very related to FQDN, and does not meet notability requirements for a article. Qjokj6567 ( talk) 19:03, 19 May 2015 (UTC)
Not sure the correct policy for this but wanted to let you know: https://www.youtube.com/watch?v=qHAb3Foa1Nw – I can't report the video because it doesn't infringe my rights, as I haven't contributed to the article. There are many other videos like this in that channel. — Preceding unsigned comment added by 77.20.177.141 ( talk) 17:51, 14 December 2014 (UTC)
Hi all. It seems this article still contains misinformation. Rather than take up tons of space here, I have written up a lengthy explanation of why the trailing dot is not part of a FQDN.
In a nutshell, and as has been pointed out by other users on this very talk page, the dot is a lexical convention only used in DNS resource records and (rarely) to control the behavior of a resolver; it is not an inherent component of a FQDN. On my side are numerous quotations from RFCs 882, 1035, 1123, 1594, 1983, 2181, 2821, 2822, and 4703. Some of these same quotations have been taken out of context by previous editors of this Wikipedia article to support conflicting assertions about the trailing dot.
I also take issue with the references for "PQDN" and "relative domain name"; see my writeup for explanation.
Before I hack away at the article, I'd like to hear your comments/criticisms, either here or in my inbox. Thanks. — mjb ( talk) 16:56, 23 December 2015 (UTC)
I have never edited a Wikipedia page. With my inexperience, I'd like to start by submitting in "talk" and learning more about how to proceed.
"including at least a second-level domain and a top-level domain"
A second-level domain is not required. "ai." is an FQDN. Https://ai. is a valid website and is live. It has an MX record. It is distinct from "ai" because it lacks the terminating dot. It is ambiguous, sometimes meant as an unqualified domain/host (in DNS, though not necessarily in SMTP email addresses). In network configurations with domain suffix searches, ai could be an unqualified name that resolves to ai.something, ai.something.something, and so on.
There is nothing in the footnoted source (or that source's source); RFCs 1594 and 3696; or logic that indicates an FQDN must have at least two labels (one being the TDL and one below that). In fact, logic proves otherwise. If a TLD couldn't, on its own, be an FQDN, there would be no such thing as a fully-qualified TLD.
The paraphrasing of RFC 1594 in the author's source states, "If you think of the DNS as a tree-structure with each node having its own label, a fully qualified domain name for a specific node would be its label followed by the labels of all the other nodes between it and the root of the tree." It is an accurate paraphrase; but neither it nor the original content rule out a node having no nodes and labels between it and the root of the tree. If a TLD has no nodes between it and the root, then none are possible to omit. In other words, the FQDN of a TLD includes all of the labels when it includes only itself, because there are no other labels to include.
There are sources that claim things like "Domain name consists of two parts, a second level domain (SLD) and a top level domain (TLD)." That particular quote is fallacious, not least because it contradicts every website that has "www" as its third-level label.
"The DNS root domain is unnamed which is expressed by having an empty label in the DNS hierarchy, resulting in a fully qualified domain name ending with the top-level domain."
There is some supporting documentation for stating the root domain's label is empty. For example, RFC 4702 states,
"To send a fully qualified domain name, the Domain Name field is set to the DNS-encoded domain name including the terminating zero-length label."
In other documentation, it is referred to as having a null name. See RFCs 2929, 5395, and 6195 all of which include, "the null or ROOT label can not the null label is usable only as root...." — Preceding unsigned comment added by Sophware ( talk • contribs) 18:40, 17 January 2019 (UTC)
This is the
talk page for discussing improvements to the
Fully qualified domain name article. This is not a forum for general discussion of the article's subject. |
Article policies
|
Find sources: Google ( books · news · scholar · free images · WP refs) · FENS · JSTOR · TWL |
![]() | This article is rated Start-class on Wikipedia's
content assessment scale. It is of interest to the following WikiProjects: | ||||||||||||||||
|
This first paragraph used to look like this:
A fully qualified domain name (or FQDN) is the human-readable name corresponding to the TCP/IP address of a network interface, as found on a computer, router or other networked device. It includes both its host name and its domain name.
I changed it. Here is my reasoning.
The statements contained in the first paragraph are incorrect. A FQDN doesn't have to be human-readable, unless in the sense that it uses human readable characters. A FQDN could be rs3927-8H.as4823.net. Is that human-readable? My point is that it has dual purpose, both human and machine.
Secondly (and more importantly), an FQDN does not correspond to ANYTHING, not by definition. There are multiple resource record types that you can use with domain names. I will point to IN TXT as a valid, but non-TCP/IP address RR as an example of why this is not true.
What i have changed the paragraph to is more correct, and does not mislead the reader into a narrow view of what DNS is capable of.
- Fudoreaper 22:28, July 29, 2005 (UTC)
I am not sure if "canonical name" is the same as and should be directed to "FQDN". I read that if one uses /etc/hosts, the first hostname on the list is considered as the canonical name. So, if the first name is a unqualified name, the canonical name is the unqualified name. It seems canonical is as opposed to aliases, and FQDN is opposed to unqualified name - they are two different concepts. That is, all the canonical and aliased names can be fully qualified, and also can be all unqualified. I read that "canonical name" is defined in RFC103.
- Ming Kin Lai
—Preceding unsigned comment added by 128.195.10.233 ( talk • contribs) 2006-09-27T19:21:35
"Any binary string can be used as the label of any resource record; a common misconception is that names are limited to a subset of ASCII characters." according to RFC1035 sec. 2.3.1, in order to be backward compatible, one should use the "let-dig-hyp" characters only.
- Yuval —Preceding unsigned comment added by 212.235.26.189 ( talk) 09:45, 19 February 2008 (UTC)
I have never heard mention of an 'absolute domain name', which we say is an alternative to 'fully qualified domain name' in the opening paragraph. Can anyone say where they've heard this, or even better, cite a source? — fudoreaper ( talk) 08:27, 18 March 2009 (UTC)
PS: I think the notion of 'ambiguity' requires context, for example, if a host 'myhost' belongs to two domains for which it has, say, different SRV records. Only in this context would the local use of 'myhost' be ambiguous, but outside of these domains, where this context is unavailable, the name is simply incomplete and likely unresolvable. Kbrose ( talk) 17:59, 18 March 2009 (UTC)
Back before I did a rewrite (see here), this article claimed: "Notice that there is a dot at the very end of the domain name, i.e. it ends ".com." and not ".com" — this indicates that the name is an FQDN. For example "myhost.bar.com" could be ambiguous, because it could be the prefix of a longer domain name such as "myhost.bar.com.au", whereas "myhost.bar.com." is a fully qualified domain name." I found this kind of bogus due to the ndot rule, but the whole article stressed the "requirement" that a FQDN must have a dot at the end. I'm not sure how much this is a "common misunderstanding" in the general population, but there was a little more text that addressed the issue. Wrs1864 ( talk) 18:00, 18 March 2009 (UTC)
A full does imply a partial. Is there a partial?
Which are the phrases to describe the distinction, please, between, with www. verus without? Such as [ my examples include en., nothing, then www.. ]:
http://www.wiktionary.org/wiki
[[ hopiakutaPlease do sign your communiqué. ~~ T hank You, DonFphrnqTaub Persina.]] 10:00, 4 September 2009 (UTC)
Please, help?
Anyone home?
[[ hopiakutaPlease do sign your communiqué. ~~ T hank You, DonFphrnqTaub Persina.]] 22:15, 8 September 2009 (UTC)
The third paragraph states that "The FQDN therefore uniquely identifies the device". For this example, this is true, but it is not universally true. The FQDN may refer to a round-robin set of machines or even a name that has no specific machine associated with it; the key is that within the complete domain name system, it points to a specific node within the tree. Corydon76 ( talk) 18:17, 6 November 2009 (UTC)
If there is to be a trailing dot at the end of a sentence, that must be clearly defined by another method than only one dot. Either use two, or use a separate box to display the example; ie.
somehost.example.com.
Was this what was actually meant? - KitchM ( talk) 20:46, 10 November 2009 (UTC)
How about an FQDN example? scope_creep ( talk) 16:01, 23 August 2010 (UTC)
My edit has been reverted by user tbhotch within several seconds (so he/she has not read the RFCs but just disliked the edit). Text of my edit was: It seems that a significant part of this article is PLAIN WRONG. See RFC 1594 (Section 5.2) for Fully Qualified Domain Name (FQDN). This RFC is cited by several other RFCs using the term FQDN. See RFC 1034 and RFC 1035 for absolute domain names (sometimes called complete domain names). The terms FQDN and absolute domain name are NOT synonyms. Maybe someone with Wikipedia formatting skills can add a hint to the article. People rely on Wikipedia but information given in the article is PLAIN WRONG. I am a UNIX admin for nearly 20 years and I do read RFCs (which are the relevant source for internet related things by definition). (I had added some asterisks to my original edit as I do not know how to format Wikipedia articles to emphasize that important information.) — Preceding unsigned comment added by 84.128.50.110 ( talk) 22:45, 30 September 2012 (UTC)
Googling suggests that PQDN is often discussed alongside FQDN, and there is a competent article at FQDN as compared to the totally unsourced dictionary definition at PQDN: it looks as if it would be better to add some description of PQDN to the FQDN article and redirect. Pam D 22:47, 20 May 2014 (UTC)
-- 74.93.100.211 ( talk) 00:25, 18 November 2014 (UTC)
Support PQDN is very related to FQDN, and does not meet notability requirements for a article. Qjokj6567 ( talk) 19:03, 19 May 2015 (UTC)
Not sure the correct policy for this but wanted to let you know: https://www.youtube.com/watch?v=qHAb3Foa1Nw – I can't report the video because it doesn't infringe my rights, as I haven't contributed to the article. There are many other videos like this in that channel. — Preceding unsigned comment added by 77.20.177.141 ( talk) 17:51, 14 December 2014 (UTC)
Hi all. It seems this article still contains misinformation. Rather than take up tons of space here, I have written up a lengthy explanation of why the trailing dot is not part of a FQDN.
In a nutshell, and as has been pointed out by other users on this very talk page, the dot is a lexical convention only used in DNS resource records and (rarely) to control the behavior of a resolver; it is not an inherent component of a FQDN. On my side are numerous quotations from RFCs 882, 1035, 1123, 1594, 1983, 2181, 2821, 2822, and 4703. Some of these same quotations have been taken out of context by previous editors of this Wikipedia article to support conflicting assertions about the trailing dot.
I also take issue with the references for "PQDN" and "relative domain name"; see my writeup for explanation.
Before I hack away at the article, I'd like to hear your comments/criticisms, either here or in my inbox. Thanks. — mjb ( talk) 16:56, 23 December 2015 (UTC)
I have never edited a Wikipedia page. With my inexperience, I'd like to start by submitting in "talk" and learning more about how to proceed.
"including at least a second-level domain and a top-level domain"
A second-level domain is not required. "ai." is an FQDN. Https://ai. is a valid website and is live. It has an MX record. It is distinct from "ai" because it lacks the terminating dot. It is ambiguous, sometimes meant as an unqualified domain/host (in DNS, though not necessarily in SMTP email addresses). In network configurations with domain suffix searches, ai could be an unqualified name that resolves to ai.something, ai.something.something, and so on.
There is nothing in the footnoted source (or that source's source); RFCs 1594 and 3696; or logic that indicates an FQDN must have at least two labels (one being the TDL and one below that). In fact, logic proves otherwise. If a TLD couldn't, on its own, be an FQDN, there would be no such thing as a fully-qualified TLD.
The paraphrasing of RFC 1594 in the author's source states, "If you think of the DNS as a tree-structure with each node having its own label, a fully qualified domain name for a specific node would be its label followed by the labels of all the other nodes between it and the root of the tree." It is an accurate paraphrase; but neither it nor the original content rule out a node having no nodes and labels between it and the root of the tree. If a TLD has no nodes between it and the root, then none are possible to omit. In other words, the FQDN of a TLD includes all of the labels when it includes only itself, because there are no other labels to include.
There are sources that claim things like "Domain name consists of two parts, a second level domain (SLD) and a top level domain (TLD)." That particular quote is fallacious, not least because it contradicts every website that has "www" as its third-level label.
"The DNS root domain is unnamed which is expressed by having an empty label in the DNS hierarchy, resulting in a fully qualified domain name ending with the top-level domain."
There is some supporting documentation for stating the root domain's label is empty. For example, RFC 4702 states,
"To send a fully qualified domain name, the Domain Name field is set to the DNS-encoded domain name including the terminating zero-length label."
In other documentation, it is referred to as having a null name. See RFCs 2929, 5395, and 6195 all of which include, "the null or ROOT label can not the null label is usable only as root...." — Preceding unsigned comment added by Sophware ( talk • contribs) 18:40, 17 January 2019 (UTC)