Issuing the show ip cef command to verify the contents of the Cisco Express Forwarding (CEF) Forwarding Information Base (FIB) is not a step in troubleshooting the incomplete marker when it appears in the output of the show adjacency command. The show ip cef command is used to display the contents of the FIB. The FIB, which is similar in concept to a routing table, is one of two databases used by CEF. The other database is the adjacency table, which is used to store nexthop information that is discovered by using Address Resolution Protocol (ARP) requests. The incomplete marker in this scenario appears in the contents of the adjacency table.
When an incomplete marker appears in the adjacency table, the cause is typically either a failed ARP request or a failure to clear a transient incomplete marker that resulted from issuing the clear ip arp command or the clear adjacency command. Therefore, you could wait 60 seconds and issue the show adjacency command again if you are troubleshooting the appearance of the incomplete marker. When the clear ip arp command or the clear adjacency command is issued, the nexthop entry will initially be marked as incomplete in the adjacency table. However, under normal circumstances, that marker should be cleared from the table after 60 seconds. In addition, you could choose to verify that ARP is sending requests by issuing the debug arp command or verify that the ARP table is populated with correct information by issuing the show ip arp command.