Which options accurately describe the function of DST-NAT and SRC-NAT?

The function of DST-NAT (Destination Network Address Translation) is to change the destination address of incoming packets to route them to a specific device within the local network. This is commonly used to allow external users to access services hosted on internal servers by translating the public IP address to the private IP address of the server. Thus, the description that DST-NAT is used to define a new destination address in the local network accurately captures this function.

The other descriptions do not reflect the primary function of SRC-NAT (Source Network Address Translation). SRC-NAT typically modifies the source address of packets leaving the internal network so they appear to originate from the router's public IP address, allowing devices in the local network to share a single public IP for outbound connections. It's not solely about preventing access; rather, it's focused on enabling connectivity while maintaining a layer of security by hiding internal IP addresses.

The reasoning behind the other functions ascribed to SRC-NAT or DST-NAT in the question may reflect misunderstanding. DST-NAT does not inherently involve packets being redirected solely to the router itself, and SRC-NAT does not prevent local network clients from accessing external networks; rather, it facilitates their access while managing how they appear to external services.