Bug #25842

DNS resolver should not be case sensitive

Added by Michael Schiessl about 4 years ago. Updated almost 4 years ago.

foreman-installer script
Target version:
Bugzilla link:
Fixed in Releases:
Found in Releases:
Red Hat JIRA:


I'm totally new here, so I'd like to say kindly hello to the project team in first.

I installed foreman on a bare metal installed CentOS7 like described in your documentation and faced against a minor bug in foreman-installer prerequsites.

The installer already fails if the hostname is case-sensitive for forward and reverse resolution only.

[root@FOREMAN ~]# foreman-installer -i
Reverse DNS does not match hostname
Your system does not meet configuration criteria
[root@FOREMAN ~]#
[root@FOREMAN ~]#
[root@FOREMAN ~]# host has address
[root@FOREMAN ~]# host domain name pointer
[root@FOREMAN ~]#

DNS names should not be case sensitive.

See also here
http ://
https ://

As a workaround I added following line to /etc/hosts esh-mgmtsrv01-t

After the workaround the installer succeeded

Associated revisions

Revision 3cded20f (diff)
Added by Ewoud Kohl van Wijngaarden about 4 years ago

Fixes #25842 - Correct DNS comparisons

DNS labels are case insenstive so regular string comparisons don't
always work. The Resolv::DNS::Name class implements the correct


#1 Updated by Ewoud Kohl van Wijngaarden about 4 years ago

  • Triaged changed from No to Yes
  • Category set to foreman-installer script
  • Found in Releases 1.20.0 added

The offending check appears to be

If you wrap the hostnames in Resolv::DNS::Name.create() you use Ruby's DNS-aware comparisons:

[1] pry(main)> Resolv::DNS::Name.create("y.z") == Resolv::DNS::Name.create("Y.Z")
=> true

This would be a great first contribution :)

Note we recently added a check to prevent uppercase hostnames. This was mostly motivated by Katello because these kind of bugs show up in more places.

That said, IMHO we should support this because the RFCs allow it.

#2 Updated by The Foreman Bot about 4 years ago

  • Assignee set to Ewoud Kohl van Wijngaarden
  • Status changed from New to Ready For Testing
  • Pull request added

#3 Updated by Ewoud Kohl van Wijngaarden about 4 years ago

  • Status changed from Ready For Testing to Closed

#4 Updated by Tomer Brisker almost 4 years ago

  • Fixed in Releases 1.22.0 added

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