Nexus# conf t 
Enter configuration commands， one per line. End with CNTL/Z. 
Nexus（config）# interface Loopback10 
% Permission denied  Nexus（config）# ？ 
no Negate a command or set its defaults 
username Configure user information. 
end Go to exec mode 
exit Exit from command interpreter 
What is the reason why this user is not able to enter configuration commands？（）

A. Cisco DCNM-LAN server users are local to the Cisco DCNM-LAN server. Creating， changing， and removing Cisco DCNM-LAN server users has no effect on user accounts on managed devices.
B. A Cisco DCNM-LAN server user that has Administrator privileges can push out changes to managed devices even if the Cisco NX-OS role that is used on the discovered device has the network operator role.
C. Cisco DCNM-LAN user roles restrict the ability of users to make changes to Cisco DCNM-LAN server settings. Cisco NX-OS user roles enforce read/write privileges on the discovered devices.
D. Cisco DCNM-LAN allows you to configure unique credentials for each discovered device or use default credentials when you do not configure unique credentials for a device.
E. Cisco DCNM-LAN can use AAA servers to authenticate users. Only TACACS servers are supported.

A. DHCP snooping commands are not available until the feature is enabled with the feature dhcp- snooping command.
B. When you enable the DHCP snooping feature， the switch begins building and maintaining the DHCP snooping binding database.
C. The switch will not validate DHCP messages received or use the DHCP snooping binding database to validate subsequent requests from untrusted hosts until DHCP snooping is enabled globally and for each specific VLAN.
D. Globally disabling DHCP snooping removes all DHCP snooping configuration on the switch.
E. Globally disabling DHCP snooping does not remove any DHCP snooping configuration or the configuration of other features that are dependent upon the DHCP snooping feature.

A. The AED is responsible for sending all unicast traffic in a site， while either node in a site can transmit multicast and broadcast.
B. The AED is responsible for load balancing all traffic for all VLANs across the transport network.
C. The AED is responsible for handling all unicast， broadcast， and multicast traffic for a given VLAN within a site.
D. The AED is responsible for MAC address dispute contention for a given VLAN.