I've got a machine (Debian jessie) used to jump to another machines, with different domains.... actually many domains.As man resolv.conf tell us, search list for host-name lookup is limited up to 6 domains or 256 characters.How can I increase the number of domains lookup?Thanks in advance.
resolv.conf limited to six domains with a total of 256 characters
dns;resolvconf
This question has been asked off and on since the 1990s.  It's still the same answer.As Jakub Jelinek of RedHat said 10 years ago, this limit is hardwired into the BIND DNS client library that is contained within GNU libc.  It's not configurable at run-time, and it's unlikely to be altered by operating system distributors as that breaks binary compatibility with some third-party programs that use this part of GNU libc.Of course, if one is capable one can always change the parameter, and recompile from source both GNU libc and all of the programs that use it.  However, this is a lot of work just to make ssh pescado look in more than 6 places in the DNS namespace tree to find a machine named pescado.  ☺Further readingJakub Jelinek (2005-09-14). DNS resolver's 'MAXDNSRCH 6' value is too small.  168253.  RedHat bugzilla.Jakub Jelinek (2006-12-15) .  RFE: More search domains in /etc/resolv.conf.  219778.  RedHat bugzilla.Jean-Marc Pouchoulon (2002-04-25). resolv.conf manage more than 6 domains.  bind-users.