Yes/No question are preceded by to be(is, am, are, was, were), auxiliary, verbs (do, does, did, have, has, had) and modals (can, will, may, must, shall. Please study the following examples. Look at the words in bold.
Sebastian Bonnet : Is your book thick?
Keanu Varia : Yes, it is.
Sebastian Bonnet : Does it have a red cover?
Keanu Varia: No, it doesn’t. It has a blue hard cover.