What command could you implement in the firewall to conceal internal IP address?

A.
no source-route

B.
no broadcast.. ..

C.
no proxy-arp

D.
no cdp run

Explanation:
The Cisco IOS software uses proxy ARP (as defined in RFC 1027) to help hosts with no
knowledge of routing determine the media addresses of hosts on other networks or subnets.
For example, if the router receives an ARP request for a host that is not on the same interface
as the ARP request sender, and if the router has all of its routes to that host through other
interfaces, then it generates a proxy ARP reply packet giving its own local data-link address.
The host that sent the ARP request then sends its packets to the router, which forwards them
to the intended host. Proxy ARP is enabled by default.
Router(config-if)# ip proxy-arp – Enables proxy ARP on the interface.
http://www.cisco.com/c/en/us/td/docs/ios/12_2/ip/configuration/guide/fipr_c/1cfipadr.html#wp1
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