API Hostname, secret key, and integration key are assigned by Duo. These are mandatory parameters and there are no default values. SecretKey and IntegrationKey support special formatting characters. The formatting is done once during the module activation.

Hostname api-aabbcczz.duosecurity.com
SecretKey aaaabbbbccccddddeeeeffffgggghhhhiiiijjjj
IntegrationKey kkkkllllmmmmnnnnoooo