Overlapping routes can all match before the longest prefix is chosen.

highlighted = computed this step

More than one row can match

The broad rows, the narrow row, and the default row all match this destination.

matching rows=4\text{matching rows}=4
Which rows matchThe destination is masked against every pinned route prefix.Longest prefix match - destination 192.168.1.130, winner 192.168.1.128/25 -> labprefixmaskdest & maskmatchnext hopwinner192.168.0.0/16255.255.0.0192.168.0.0yescoreno192.168.1.0/24255.255.255.0192.168.1.0yesfloor-1no192.168.1.128/25255.255.255.128192.168.1.128yeslabyes0.0.0.0/00.0.0.00.0.0.0yesdefaultno

The default row is broad

The default row has prefix length 0, so destination AND mask is also all zero.

/0/0
Which rows matchThe destination is masked against every pinned route prefix.Longest prefix match - destination 192.168.1.130, winner 192.168.1.128/25 -> labprefixmaskdest & maskmatchnext hopwinner192.168.0.0/16255.255.0.0192.168.0.0yescoreno192.168.1.0/24255.255.255.0192.168.1.0yesfloor-1no192.168.1.128/25255.255.255.128192.168.1.128yeslabyes0.0.0.0/00.0.0.00.0.0.0yesdefaultno

Matching is not choosing yet

A yes in the match column only says the row is eligible. The next lesson chooses among eligible rows.

eligible rows=4\text{eligible rows}=4
Which rows matchThe destination is masked against every pinned route prefix.Longest prefix match - destination 192.168.1.130, winner 192.168.1.128/25 -> labprefixmaskdest & maskmatchnext hopwinner192.168.0.0/16255.255.0.0192.168.0.0yescoreno192.168.1.0/24255.255.255.0192.168.1.0yesfloor-1no192.168.1.128/25255.255.255.128192.168.1.128yeslabyes0.0.0.0/00.0.0.00.0.0.0yesdefaultno

Summary

The router first recomputes every match row, then chooses the most specific matching prefix.

matches=4\text{matches}=4
Which rows matchThe destination is masked against every pinned route prefix.Longest prefix match - destination 192.168.1.130, winner 192.168.1.128/25 -> labprefixmaskdest & maskmatchnext hopwinner192.168.0.0/16255.255.0.0192.168.0.0yescoreno192.168.1.0/24255.255.255.0192.168.1.0yesfloor-1no192.168.1.128/25255.255.255.128192.168.1.128yeslabyes0.0.0.0/00.0.0.00.0.0.0yesdefaultno