When and How did Draco find out his father was a Death Eater?

I'm just going to guess he had little idea at the start of the series, I mean you don't really entrust such information to an eleven year old. That said he must have notated some people acted funny around his father. I'm going to say the once he new about Death Eaters he would have connected to dots, but the wizarding youth don't seem to know much. Also even if he did know about Death Eaters he may not have thought his father had been one. The other possibility is that Draco knew his father was a Death Eater but didn't know really know what that meant.

He probably knew by The Goblet of Fire. That said he might not even have known when they were torturing muggles. I mean his father would have expressed his hatred towards muggles before then so it's not altogether unlikely Draco didn't think much of it.

I can't imagine Lucius sitting Draco down and saying " It's time you know, that not long before you were born I was a death eater." I mean it's not the sort of thing you can just tell some one especially if you had no reason to. Is it possible he figured out himself or someone else tipped him off? Maybe Moody (or really Crouch Jr. I guess.)