In this term, we learned that SNMP (Simple Network Management Protocol) is a network management protocol widely used among enterprises for collecting and organizing information about managed devices such as switches, routers, and firewalls. This protocol uses UDP as its transport protocol because it has no need for the overhead of TCP. Unfortunately, SNMP implementations could have a variety of different problems and issues. Therefore, it's important that you know how to troubleshoot SNMP network monitoring issues. 

For this question, explain in detail your methodology to troubleshoot the following issues. 

Make sure to justify your answer with an example.

 a) SNMP packets failed to pass through the network due to firewall implementation. 

b) Network management system (NMS) unable to receive traps from a switch exists in the network. 

 c) Duplicate SNMP Engine ID were found on different devices on the network.