Longest prefix match
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Because each entry in a routing table may specify a network, one destination address may match more than one routing table entry. The most specific of the matching table entries — the one with the highest subnet mask — is called the longest prefix match. It is called this because it is also the entry where the largest number of leading address bits of the destination address match those in the table entry.
When the address 192.168.20.19 needs to be looked up, both entries in the routing table "match". That is, both entries contain the looked up address. In this case, the longest prefix of the candidate routes is 192.168.20.16/28, since its subnet mask (/28) is higher than the other entry's mask (/16), making the route more specific.
Routing tables often contain a default route, which has the shortest possible prefix match, to fall back on in case matches with all other entries fail.