For those who may not be familiar with Commack:
Commack is a hamlet (an unincorporated area) partly in the southeast part of the Town of Huntington and partly in the southwest part of the Town of Smithtown, in the northwest part of Suffolk County, along the Smithtown/Islip town line.
Beginning on the north and moving in a clockwise direction, the Hamlet of Commack in the Town of Huntington and the Town of Smithtown is bordered on the north by the Hamlet of East Northport, Town of Huntington, and the Hamlet of Fort Salonga and the Hamlet of Kings Park in the Town of Smithtown; on the east by the Hamlet of Smithtown and the Hamlet of Hauppauge in the Town of Smithtown; on the south by the Hamlet of Brentwood in the Town of Islip (the Smithtown/Islip town line) and the Hamlet of Dix Hills in the Hamlet of Huntington; and, on the west by the Hamlet of Dix Hills and the Hamlet of Elwood in the Town of Huntington.
The Hamlet of Commack has a different border than does the "Commack, NY 11725" postal zone (i.e., a place can have a "Commack, NY 11725" mailing address and not be in the Hamlet of Commack): places that have a "Commack, NY 11725" mailing address that are not in the Hamlet of Commack are in the Hamlet of Elwood in the Town of Huntington and in the Hamlet of Smithtown in the Town of Smithtown.
For a good set of town-by-town maps showing all the villages and hamlets in each of LI's 13 towns (3 in Nassau County and 10 in Suffolk County):
Excellent Long Island Geographic Resource