By default it will take 10 seconds for authentication to fail due to an unresponsive RADIUS server
before a Cisco Nexus series switch reverts to another RADIUS server or local authentication. What is
one efficient way to improve the reaction time to a RADIUS server failure?

A.
Decrease the global RADIUS retransmission count to 1.

B.
Decrease the global RADIUS timeout interval to 5 seconds.

C.
Configure the RADIUS retransmission count and timeout interval per server, versus globally.

D.
Configure per server a test idle timer, along with a username and password.

Explanation:
You can monitor the availability of RADIUS servers. These parameters include the username and
password to use for the server and an idle timer. The idle timer specifies the interval during which a
RADIUS server receives no requests before the Nexus 5000 Series switch sends out a test packet. You
can configure this option to test servers periodically. The test idle timer specifies the interval during
which a RADIUS server receives no requests before the Nexus 5000 Series switch sends out a test
packet. The default idle timer value is 0 minutes. When the idle time interval is 0 minutes, the Nexus
5000 Series switch does not perform periodic RADIUS server monitoring.

http://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus5000/sw/configuration/guide/cli
_rel_4_0_1a/CLIConfigurationGuide/sec_radius.html