Unicast Reverse-Path-Forwarding (RPF) JN0-105 Practice Questions (Page 3)

Questions 11–15

1. 11foundation · easy

   What is the impact of a unicast RPF failure on a packet?

   • AThe packet is silently discarded
   • BThe packet is sent back to the source with an ICMP error
   • CThe packet is forwarded to the default route
   • DThe packet is logged and then forwarded
   Reveal Solution Discussion Select an answer first
2. 12application · medium

   A Junos router with strict-mode RPF enabled on its upstream interface is dropping traffic from a legitimate customer. The customer's source prefix is advertised via BGP and is reachable through the upstream interface. However, the router also has a static route for a more specific prefix within that customer's range, pointing to a different interface. What is the most likely cause of the RPF failure?

   • AThe BGP route is not installed in the forwarding table
   • BThe customer's traffic is arriving on the wrong interface
   • CStrict-mode RPF does not work with BGP-learned routes
   • DThe more specific static route causes the source to be reachable via a different interface
   Reveal Solution Discussion Select an answer first
4. 13foundation · easy

   Which Junos firewall filter action is used to enable unicast RPF?

   • Arpf-check
   • Bdiscard
   • Creject
   • Dcount
   Reveal Solution Discussion Select an answer first
5. 14expert · hard

   A Junos router with strict-mode RPF on interface ge-0/0/0 is dropping traffic from a legitimate source. The source address is 203.0.113.0/24, and the route to this prefix is via ge-0/0/0. However, the router also has a static route for 203.0.113.128/25 via ge-0/0/1. What is the most likely reason for the RPF drops?

   • AStrict-mode RPF does not work with static routes
   • BThe route via ge-0/0/0 is not installed in the forwarding table
   • CThe traffic is arriving on the wrong interface
   • DThe source address falls within the more specific static route, which points to a different interface
   Reveal Solution Discussion Select an answer first
6. 15application · medium

   Your Junos router is connected to two ISPs for redundancy. Due to the way BGP selects paths, return traffic for some destinations is sent out a different interface than the one on which the corresponding inbound traffic arrives. You need to enable RPF to block spoofed packets without disrupting legitimate traffic. What should you do?

   • AEnable strict-mode RPF on both ISP-facing interfaces
   • BEnable strict-mode RPF on one ISP interface and loose-mode on the other
   • CDisable RPF and rely on BGP prefix filtering
   • DEnable loose-mode RPF on both ISP-facing interfaces
   Reveal Solution Discussion Select an answer first