Can't resolving (sub)domains starting with an underscore (Server not found Firefox can't find the server at...)
Categories
(Core :: Networking: DNS, defect)
Tracking
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People
(Reporter: taiyuan123, Unassigned)
References
Details
User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:75.0) Gecko/20100101 Firefox/75.0
Steps to reproduce:
I'm not sure if it's relating to Webview in Android system, and I don't know if Firefox for Android uses the webview for something. But I have very similar issues when accessing a website whose domain starting with an underscore (_), in both Webview Broswser and Firefox.
I have already submitted a bug report to Android and more details can be found in it: https://issuetracker.google.com/issues/154694663
Actual results:
Simple version:
In domain zone example.com, add an A record:
_abc => 185.199.108.153 (I use GitHub Pages IP here for quick demonstration).
.. and a CNAME record:
cname => _abc.example.com
Visiting sites http://_abc.example.com and http://cname.example.com both fail with error message "Server not found Firefox can't find the server at ...", looks like it's a DNS resolving problem but maybe not. Details please see the issue link in Android bug tracker attached above.
Expected results:
At least http://cname.example.com should be working, and further http://_abc.example.com may be supported as well.
By the way, Chrome for Android doesn't have such issue, both sites can be displayed, though the page is a 404 error page from GitHub Pages.
The desktop Firefox for Windows doesn't have such issue too, where both sites can be accessed.
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Comment 1•4 years ago
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I am not sure if this is a valid request - underscores are invalid characters in hostnames.
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Comment 2•4 years ago
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Moving this to Core / Networking::DNS because I do not know what the right answer here is.
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Comment 3•4 years ago
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(In reply to taiyuan123 from comment #0)
_abc => 185.199.108.153 (I use GitHub Pages IP here for quick demonstration).
.. and a CNAME record:
cname => _abc.example.com
I think that RFC 1123 section 2.1 doesn't allow this. Valentin, what do you think?
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Comment 4•4 years ago
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(In reply to Michal Novotny [:michal] from comment #3)
(In reply to taiyuan123 from comment #0)
_abc => 185.199.108.153 (I use GitHub Pages IP here for quick demonstration).
.. and a CNAME record:
cname => _abc.example.comI think that RFC 1123 section 2.1 doesn't allow this. Valentin, what do you think?
The RFC doesn't allow it, but in practice it is sometimes used, and we should try to support it.
But as I mention in bug 1630439 comment 9 there isn't much we can do about it. It's an Android issue.
Description
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