Thanks for your replies,
I found the ticket, that's why I asked : sounds to me a hard job to plan, especially now with DNSEC validation (and not sure that it would have a real added value)... A "natural" way for sssd if really a plan might be to catch zones from one of the ldap bakend available for bind ?
Anyway, the real reason I'm investigating : I'm distributing sudo rules with ldap and I want to use hostname to tell which host the rules appliy on. I have told in nsswitch.conf to query the DNS to find out the hostname but I'm not sure about how is collected the hostname from the dns in the checking process (especially if the machine has more than one interface) ? Is the label considered as being the hostname the reverse of the IP adress for the default interface ?