Cisco Catalyst 3650 series Command Reference Manual page 846

show ip dhcp snooping statistics
DHCP Snooping Statistic
Interface Down
Unknown output interface
Reply output port equal to input port
Packet denied by platform
Command Reference, Cisco IOS XE Everest 16.5.1a (Catalyst 3650 Switches)
820
Description
Number of times the packet is a reply to the DHCP relay agent,
but the SVI interface for the relay agent is down. This is an unlikely
error that occurs if the SVI goes down between sending the client
request to the DHCP server and receiving the response.
Number of times the output interface for a DHCP reply packet
cannot be determined by either option-82 data or a lookup in the
MAC address table. The packet is dropped. This can happen if
option 82 is not used and the client MAC address has aged out. If
IPSG is enabled with the port-security option and option 82 is not
enabled, the MAC address of the client is not learned, and the reply
packets will be dropped.
Number of times the output port for a DHCP reply packet is the
same as the input port, causing a possible loop. Indicates a possible
network misconfiguration or misuse of trust settings on ports.
Number of times the packet has been denied by a platform-specific
registry.