Consider the following command and an abbreviated version of its output:
$ netstat -nr
Kernel IP routing table
Destination Gateway Genmask Flags Iface
192.168.165.0 0.0.0.0 255.255.255.0 U eth0
127.0.0.0 0.0.0.0 255.0.0.0 U lo
0.0.0.0 192.168.165.1 0.0.0.0 UG eth0

What is the default Gateway?

A.
192.168.165.1

B.
255.0.0.0

C.
255.255.255.0

D.
0.0.0.0

E.
192.168.165.0

Explanation:
From http://www.freebsd.org/doc/handbook/network-routing.html:
For one machine to be able to find another over a network, there must be a mechanism in place to describe how to get from one to the other. This is called routing. A route is a defined pair of addresses: a destination and a gateway. The pair indicates that if you are trying to get to this destination, communicate through this gateway. There are three types of destinations: individual hosts, subnets, and default. The default route is used if none of the other routes apply.

Consider this output of netstat
# netstat -r
Kernel IP routing table
Destination Gateway Genmask Flags MSS Window irtt Iface
192.168.165.0 * 255.255.255.0 U 0 0 0 eth0
link-local * 255.255.0.0 U 0 0 0 eth0
default 192.168.165.1 0.0.0.0 UG 0 0 0 eth0
When you call netstat without the -n option you can see that 0.0.0.0 becomes "default", indicating the default route, and thus the default gateway.