Understanding dot in the end of hostname
This is a very popular mistake admins make - it’s missing . i.e dot in the end of hostname. This causes serious problems (and lot of frustration!).
E.g taking example of popular Google’s cname record ghs.google.com. As we know if one would like to use mail.domain.com., he has to point the CNAME record to “ghs.google.com”. Now here if one misses dot in the end of ghs.google.com. - it will give a real value like: