A Linux administrator has configured a Linux system to be used as a router. The administrator confirms that two network adapters are properly installed and functioning correctly. In addition, the output of the iptables –L command appears to contain a complete firewall configuration.

Which of the following commands does the administrator need to issue for the router to be fully functional?

A. echo “1” > /proc/sys/net/ipv4/ip_forward

B. echo “0” > /proc/sys/net/ipv4/tcp_abort_on_overflow

C. echo “0” > /proc/sys/net/ipv4/max_connections

D. echo “1” > /proc/sys/net/ipv4/ip_default_ttl