Hi Ruzica,
After you changed the entries in the /etc/hosts file did you restart the sapinst from the beggining or just closed and continued, reason why im asking i did a install aqbout 2 weeks ago where i also had the error with the reverse lookup so i changed the etc/hosts file and start sapinst again with SAPINST_USE_HOSTNAME=DBNAME and the problem did not appear this round
Best Regards
Marius