route question

i am new in network field, i have 3 question , hope you dorp me a answer even you answer me one question. look for your advice.

1.)can tell me when the route troubleshooting, why we need to off the ARP ?

2.)What is the best way to traubleshoot the routed problem?

3.)The best differentiate between static route and default route.

Am i truth, if i descriptive static route and default route as below.

static route is for only one specific subnet pass the traffic

is default route is for all different subnet in the network pass the traffic?

From jack