For the description of URPF technology, which of the following options are correct?

The main function is to prevent network attacks based on source address spoofing.

In strict mode, it does not check whether the interface matches. As long as there is a route to the source address, the message can pass.

The loose mode not only requires corresponding entries in the forwarding table, but also requires that the interface must match to pass the URPF check.

Use URPF's loose mode in an environment where routing symmetry cannot be guaranteed.