Use this stock to make Matzo Ball Soup with Carrots and Dill. Leaving the skins on the onions adds to the rich golden color of the stock.
Rinse chicken quarters and necks under cold water and place in an 11-quart stockpot. Cut onions, carrots, and celery in half and add to pot along with bay leaves, peppercorns, and dill sprigs. Add enough cold water to cover, about 4 1/2 quarts.
Bring water to a boil. Reduce heat to medium low and simmer, skimming off any scum that rises to the surface, about 4 hours.
Remove pot from heat and strain broth through a cheesecloth-lined sieve, discarding solids. Let broth cool to room temperature and refrigerate overnight. Remove any solidified fat from the surface (and save for cooking, if desired). Broth can be kept refrigerated for 2 days or frozen.