300-710 SNCF: Securing Networks with Cisco Firewalls

Question

A network administrator is deploying a new Cisco Secure Firewall Threat Defense (FTD) firewall. After deploying Cisco Secure FTD, inside clients experience intermittent connectivity with one another. While reviewing a packet capture on the Secure FTD firewall, the administrator observes that Secure FTD responds to every ARP request on the inside network. Which action must the network administrator take to resolve the issue?

Explanation

An incorrect or overly broad static/identity NAT rule can cause Cisco Secure FTD to use proxy ARP for addresses on the directly connected inside network. If the firewall answers an ARP request before the actual host, clients send peer traffic to the firewall instead, causing intermittent connectivity. Correcting the NAT rule and disabling its inappropriate proxy ARP behavior resolves the problem.

Learn more

Cisco Secure Firewall Device Manager Configuration Guide, Version 7.7 — Network Address Translation

300-710 SNCF: Securing Networks with Cisco Firewalls

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Notes

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