{"id":"pmtud-requires-icmp-allowed-sg-and-nacl","text":"Path MTU Discovery (PMTUD) requires ICMP traffic to be allowed in both security groups and NACLs; NACLs can block ICMP even if security groups allow it.","truth_value":"IN","source":"entries/2026/03/11/AWSEC2-latest-UserGuide-network_mtuhtml.md","source_url":"","source_hash":"2a5ba8fb82b39ee9","justifications":[],"dependents":[],"metadata":{},"explanation":{"steps":[{"node":"pmtud-requires-icmp-allowed-sg-and-nacl","truth_value":"IN","reason":"premise"}]}}