On switch R1 you issue the “udld enable” global command. What does this command
accomplish?

A.
Enables all fiber-optic LAN ports for Unidirectional LINK Detection (UDLD)

B.
Enables all copper media LAN ports Unidirectional Link Detection (UDLD)

C.
Overrides the default UDLS setting for all ports

D.
Globally enables all ports on the device for Unidirectional Link Detection (UDLS)

E.
None of the other alternatives apply

Explanation:
Enabling UDLD Globally
Beginning in privileged EXEC mode, follow these steps to enable UDLD globally on all fiberoptic interfaces on the switch:
Command Purpose
Step 1 configure
terminal
Enter global configuration mode.
Step 2 udld enable Enable UDLD on all fiber-optic interfaces on the
switch. UDLD is disabled by default.
This command affects fiber-optic interfaces
only. Use the udld interface configuration
command to enable UDLD on other interface
types.
An individual interface configuration overrides
the setting of the udld enable global
configuration command.
Step 3 end Return to privileged EXEC mode.
Step 4 show udld Verify your entries.
Step 5 copy runningconfig startupconfig
(Optional) Save your entries in the configuration
file.
To disable UDLD globally on fiber-optic interfaces, use the no udld enable global
configuration command.
Reference:
http://www.cisco.com/en/US/docs/switches/lan/catalyst3550/software/release/12.1_4_ea1/co
nfiguration/guide/swudld.html