Normally, a person would knit the whole sock on DPNs, but I read a great tip a few years ago saying that the ribbing (or everything down to the heel really!) can be knitted on a straight needle, and then the seam sewn up later. I really prefer doing it this way, because:
a) I hate using DPNs to knit purl rows. I find it very awkward and can't be bothered practicing until it goes more smoothly. Life's too short!
b) I hate knitting with DPNs full-stop! They are a pain in the arse! Not to mention in your stomach where they stick into you. The less I have to use them, the better. (Now I'm wondering why I bother to make socks at all?!)
c) It's easier to see where you are up to and follow the ribbing pattern.
d) The cast-on end of the yarn is far enough away from your live knitting when you do transfer to the DPNs that it doesn't get mixed up in what you're doing and piss you off.
The only drawback is having to sew up the seam when you are finishing the socks. But the cast on yarn end is already there and you already have thread it onto a needle to weave it in anyway, so it's not a huge inconvenience.
Here is sock no.2 at the heel stage:
Yes, I know, it looks like the cat puked on my instructions and I stuck a whole bunch of knitting needles in it, but I know what I'm doing! Mostly. I made a pair of socks from this pattern once before, many years ago, ended up with the most horrible, vomit-inducing, blood-chilling pair of socks known to man. This was not the pattern's fault. It was because I'd used bargain basement black acrylic and had never used DPNs before. Yeah, I tend to bite off more than I can chew sometimes. The pattern, however, was technically perfect and easy to understand. So theoretically these socks should turn out to be just fine. Hmm.
* Not that it was all smooth sailing until that point!: