M04 Q19 - Does Spring Boot do component scanning? Where does it look by default?

Yes, Spring Boot is performing component scan, because @SpringBootApplication annotation is enabling component scanning with usage of @ComponentScan annotation.

By default, Spring Boot will search for @Component annotated classes within the same root package as @SpringBootApplication annotated class.

You can change this behavior by adding additional packages to scan with scanBasePackages or type-safe version of it scanBasePackageClasses within @SpringBootApplication annotation.