For example, $3^b \mod 5$ will cycle through all number between $0$ and $5$:
$3^1 \mod 5 = 3$,
$3^2 \mod 5 = 4$,
$3^3 \mod 5 = 2$,
$3^4 \mod 5 = 1$,
$3^5 \mod 5 = 3$
Another example is
$11^b \mod 13$,
$2^b \mod 5$,
$3^b \mod 7$
Example of modulo that does not cycle through all number between $0$ and $c$ is
$2^b \mod 7$
What are the required condition for $a^b \mod c$ to cycle through all number between $0$ and $c$? is there any material/reference for this?