Using prefixes for forwarding

• We don't list every IP number on the Internet - the table would be huge
• Instead, the forwarding table contains prefixes (network numbers)
• "If the first /n bits matches this entry, send the datagram this way"
• If more than one prefix matches, the longest prefix wins (more specific route)
• 0.0.0.0/0 is "default route" - matches anything, but only if no other prefix matches

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