how to get DNS suffix?

Hi,i am using DNSgethostbyname() to get host for my device. and host name is hardcoded as say “myhost”. i cant resolve it as DNSgethostbyname(“myhost”). i need dns suffix so that i can call DNSgethostbyname(“”). i tried my self to locate something in aceCallbacks.c but get nothing. can someone guide me. regards shyam