Final answer:
To enable Dynamic ARP Inspection (DAI) for a specific VLAN such as VLAN 11, after entering the command for that VLAN, no additional command is strictly necessary. However, further configuration may be required to fully operationalize it, such as setting trusted interfaces or validation checks.
Step-by-step explanation:
The command you've entered, "ip arp inspection vlan 11", configures Dynamic ARP Inspection (DAI) for VLAN 11. To enable DAI on the device, you must enter global configuration mode and use the command "ip arp inspection vlan" along with the VLAN numbers you want to enable DAI for. You've already specified VLAN 11, so the additional command required to fully enable DAI for this VLAN is "ip arp inspection vlan 11".
However, for DAI to operate as expected, you might also configure additional settings. For example, the "ip arp inspection trust" command identifies trusted ports that do not require ARP inspection, the "ip arp inspection validate" command determines what validations DAI should perform, and the "ip arp inspection limit" command sets rate limits for ARP packets, which can help mitigate certain types of attacks. These commands are situationally important but not strictly necessary just to enable DAI.