An organization uses IP address block 203.0.113.0/24 on its internal network. At the border router, the network administrator sets up rules to deny packets with a source address in this subnet from…

BGP route hijacking manipulates routing table advertisements to redirect traffic paths, not packet-level source or destination address filtering at a border router.

Bogon filtering targets globally unallocated or reserved IP ranges, not an organization's own legitimate internal subnet.

IP spoofing involves crafting packets with a forged source IP address to impersonate a trusted host. By blocking inbound packets that claim to originate from the internal subnet and outbound packets destined for it, the administrator enforces BCP 38-style filtering that prevents external attackers from injecting spoofed-source traffic into the network and stops internal addresses from being misused in outbound flows.

Man-in-the-middle attacks involve intercepting communications between two parties, a threat not mitigated by filtering based on a specific internal subnet's source or destination address.

Amplified DDoS attacks exploit UDP reflection to magnify traffic volume toward a victim, which is unrelated to ingress or egress filtering of an internal address block.