Exam HPE6-A73 topic 1 question 53 discussion

Its B 1) Try NH 1.1.1.1 (Seq 10) 2) Try NH 2.2.2.2 (Seq 20) 3) Try default NH 3.3.3.3 (Seq 30) 4) Match interface null, which means drop the packet. (Seq 40) C is not correct, as interface null action will drop packets before the fallback to routing table can be leveraged.

C is correct... If 1.1.1.1 is not reachable then next hop uses 2.2.2.2 if both of these are unreachable then normal routing table is used..and only if no route is available in routing table then default next-hop will kick-in

"If the highest priority list entry next-hop router or tunnel interface is reachable - that list entry is chosen, the search is stopped, and the traffic is forwarded to the next-hop router or interface for the entry. If the highest priority list entry next-hop router or tunnel interface is not reachable, the next highest priority list entry reachability is determined and used if reachable, otherwise the process continues down the list. If none of the routers in the list are reachable, the packet may be dropped (through the null interface entry if configured) or forwarded according to a system route table entry." If the null interface wasnt there it woulduse system routing, but since it is: drop

B: is the closest: If none of the routers in the list are reachable, the packet may be dropped (through the null interface entry if configured) or forwarded according to a system route table entry.

Page 905 Study Guide: The figure shows that 4 packets have arrived at some interface, sitting in a queue, waiting for service. If the ingress buffer used a single queue, Head Of Line (HOL) blocking could delay traffic. This occurs when the first packet in the queue (at the “head of the line”) is destined out a congested port, it delays all packets behind it, even though those that are destined to noncongested ports. | AOS- CX switches use an intra- switch queuing method called Virtual output Queuing ( VoQ ). VOQ prevents this problem by providing deep ingress buffers with separate queues for each egress port. [Aruba Networks]

Answer: B.

B: If none of the routers in the list are reachable, the packet may be dropped (through the null interface entry if configured) or forwarded according to a system route table entry.

Answer is B. A PBR action list is processed from the top down like an ACL. After the three nexthop entries, there's an interface null entry. This will drop all traffic that matches on the pbr-action-list.

I think C is correct, firstly 1.1.1.1, if not active ->2.2.2.2, if not active->Routing Table, if no matched-> 9.9.9.9, if not active-> interface Null.

From manual: If none of the routers in the list are reachable, the packet may be dropped (through the null interface entry if configured) or forwarded according to a system route table entry.

Answer is B interface null means that if all three are unreachable packets are dropped, only B works for me: The active entry is the one with the lowest sequence number – the one entered first, by default. (1.1.1.1) This next hop is used exclusively unless that address becomes unavailable. Within 5 seconds, the router uses the next entry – 2.2.2.2. If both of those are down, then the router uses the default- nexthop 9.9.9.9. If all three are down, the interface null action ensures packets are merely thrown away. If you omit the interface null command, then the router falls back to using destination- based route table entries.

B is correct

B should be the correct one.

The answer is B it will fall thru like an ACL

I think its C. If nexthop 1.1.1.1 is unreachable it will try nexthop 2.2.2.2.. If that one is also unreachable it will go toward the default-nexthop policy. Book explains default-nexthop as: Used if no specific route exists in routing table. So i believe it will first look at the routing table to foward the traffic, if there is no route there.. It will try 9.9.9.9, if that one is also unreachable he will drop the traffic because of interface null.

D is correct: the second instruction overwrite the first one.

I think it's b. PBR action list works like an ACL. Every entry is checked one by one and the first match is used. If the next hops are unavailable they don't match and it comes to interface null which iss the equivalent to dropping traffic.