Say you are a fine Network Engineer, in a situation where you were asked work together with Server team to change the IP address of particular servers. During assessment, you found where the IP connected to which switchport by ARP and MAC address checking.
During execution (which already gone through series of administration process, change meeting, announcement, etc. Then you realize, what if this servers has teaming configuration? As a curious person, you check to Server team, “Hi dude, your server has teaming?”, “Yes”.
You have no idea where the other ports is connected. Checking from inventory, monitoring tools, or interface description, you cannot rely on those, since they are just writings, not the actual. People might have change without updating the documentation.
So, come your Network Engineer sense, to fix this issue. Poking the server guy, “dude, I need to shut down 1 port to check other port it uses for teaming. Ok ?”, “Ok, dude.”
The IP still not reachable. Damn.
The IP not reachable. Worse. Damn.
(Hitting my head). What a dumb.
Epilog: finally it’s solved.