Whether pasta is fresh from the supermarket or dried, or homemade will affect the way it cooks.
The best way to check is to taste it. Does it bite through easily? Does it give a little resistance but not so much as to make it hard? If so you have perfect pasta.
Remember that when you add your sauce to the pasta it continues cooking so bear this in mind when you check your pasta.
Rough cooking times:
Spaghetti and linguine takes between 6 and 7 minutes to cook
Rigatoni, fusilli and all twisted and shaped pasta take about 7 – 8 minutes
Sometimes pasta, like lasagne sheets are cooked for a long time in the sauce and you want them reasonably well done anyway.
Always make sure that all your pasta is cooking separately. Don’t just throw it into boiling water and expect it to cook – sometimes spaghetti, for example, sticks together and never cooks, so give it a stir to separate.