Capture real-world network traffic so you can replay it later / elsewhere for development and testing. An example is given using IPFIX (AppFlow), but directly relevant to UDP Syslog too.
Network incompatibilities do happen and sometimes you need to be a little more forgiving in order to let the traffic flow. An example of where some Cisco behaviour was running foul of Linux.
Disabling IPTables connection tracking for DNS can resolve problems due to too many connections in the connection table.
NFS locking can impede the performance of your clustered application. Learn how to capture and analyse NFS traffic to see where your locking issues are.