When trying to rate a shipment with an Alaska location as the origin and/or destination, you are required to also enter the port used.  Once the port is selecting, entering the port zip code is also required to assist in mileage calculations.  Here are the zip codes Daycos uses for those port locations:

SITKA, AK: 99835; 99836
JUNEAU, AK: 99802
KODIAK, AK: 99615
CORDOVA, AK: 99574
WRANGELL, AK: 99833
ANCHORAGE, AK: 99501
FAIRBANKS, AK: 99701
KETCHIKAN, AK: 99919
PETERSBURG, AK: 99833