Asking for referrals upfront

I've received different opinions on how to go about broaching the subject of referrals during informational interviews. A person at my college (target) has told me that at the end of a call I should just try and hint at a referral ('Is there any way I can maximise my chances of landing this internship', 'Is there anyone else i should talk to' etc...) and hopefully they'll offer to help by putting in a good word with HR, while relatives working in finance jobs have told me that I should just be upfront and ask them 'Do you think a referral would help me with this internship?', since most people won't have the time or effort to figure out you want a referral. Which do we think is the better strategy?

Just relating two recent experiences where I tried my relatives approach: first guy (SVP), did not actually know what a referral was when I brought it up ('Do you reckon a referral would help me with this internship') and just assumed i was talking about job references (I was too embarrassed to correct him), but otherwise the conversation was nice and I think I could potentially reach out to him again about it later; second guy (some sort of director-level role) seemed slightly impatient from the start ('I've got another call in 15 minutes'), and cut straight to the chase ("what can I help you with?"): when I broached the subject of referrals, he offered to let me put his name down, but then made sure to impress on me that this was probably useless since he didn't really know me at all.

This begs a second question: how useful is a referral if the guy doesn't really know you at all (even if he's a ED or MD)? If it's not that useful, how do you obtain a more valuable referral? Do you need to "work" each contact for longer than just a single phone call/cup of coffee (so they get to know you) before you try getting a referral out of them?