“Target did not respond. It might be down or access is denied” is a generic error that is returned when the discovery of SNMP devices such as printers, switches or access points fails.

It could be either due to:

• Device not responding
• Invalid credentials

SNMP does not give an active answer when you try to contact it with invalid credentials. It just drops traffic silently. This is why you can’t tell the difference between traffic not reaching the switch and invalid credentials.

Things to investigate:

• Using the correct protocol? SNMPv1, SNMPv2c, SNMPv3?
• For SNMPv1/v2c: Correct community string?
• For SNMPv3: Correct user? password?
• For SNMPv3: Correct authentication protocol and privacy protocol?

If any of these are wrong the switch will most likely not respond and you might see “Target did not respond. It might be down or access is denied”.