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CCNP Route 300-101 Exam With Complete Solutions Latest Update
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CCNP Route 300-101 Exam With CompleteSolutions Latest Update
What is process-based switching? - ANSWER *Process-based switching* consumes CPU
resources to switch packets and will be referred to as "IP Input" in the CPU table.
What is fast switching? - ANSWER *Fast switching* stores the data in the "Fast Switching
Cache" for faster look-ups, thus giving the CPU more breathing room.
What is the weakness with fast switching as compared to CEF? - ANSWER *Fast switching*
requires the first packet to be analyzed by the CPU before entering the cache and does not
actively monitor the routing table so the cached entry aging out may take a bit of time.
What does the acronym CEF stand for? - ANSWER *Cisco Express Forwarding.
What is CEF? - ANSWER *CEF* caches information in pre-populated cache and downloads
information from the various tables as soon as available to take the load off the CPU.
What are some packets that cannot be CEF-switched? - ANSWER Some packets that cannot be
CEF-switched are ARP requests, packets that require a router CPU reply for, MTU too large,
TTL expiring, routing protocol traffic, cdp, lldp, packets needing encryption.
What does the FIB stand for? - ANSWER *Forwarding Information Base.*
What is the FIB? - ANSWER *FIB* is a shadow copy of the routing table used to assist in
CEF-switching.
What show command would verify CEF? - ANSWER show ip cef [detail]
,What is the adjacency table? - ANSWER The adjacency table is pre-populated L2 tables (ARP,
Frame-Relay) used to assist in CEF-switching.
What happens if FIB does not have a particular IP address? - ANSWER In the event that FIB
does not have a particular IP address, an ARP request is broadcast out so that it may appear in
the FIB as 'attached', which means there was a successful lookup.
What is adjacency type Glean? - ANSWER *Glean* in the adjacency table means to glean the L2
information to forward the L3 packet. The request will be punted to CPU in order to do an ARP
request, but if there is no reply, entry stays as Glean until it ages out.
What is the adjacency type Null? - ANSWER *Null* in the adjacency table denotes a valid packet
to be dropped. It can happen for various reasons. Most often it is due to null0 route and the
switching is processed in hardware.
What does adjacency type drop mean? -ANSWER *Drop* in adjacency table means a valid
packet should be dropped. It mostly happens because there is no valid route or the packet itself
has a problem.
What is the adjacency type Discard? - ANSWER *Discard* in the adjacency table refers to a
valid that needs to be dropped. This most commonly happens because there are security
policies in place such as an ACL.
What does the adjacency type Punt mean? - ANSWER *Punt* in the adjacency table works like
Glean as packets will be forwarded to the CPU. This happens for packets that are destined for
the processor in the first place.
What show command would you run to check the adjacency table? - ANSWER show adjacency
What is Unicast Flooding? - ANSWER *Unicast Flooding* occurs when there is no entry in L2
table (CAM) and packets are flooded out of every interface in VLAN other than the receiving
,interface.
How do you minimize Unicast Flooding? - ANSWER *Unicast Flooding* can be minimized by
allowing the ARP entry expire earlier than CAM entry so when the CAM entry expires, the ARP
entry would have already repopulated.
What configuration command would block Unicast Flooding? - ANSWER Router(config-if)#
switchport block unicast
What are out-of-order packets? - ANSWER *Out-of-order packets* are packets that arrive in a
different order than they were sent. This can be caused by asymmetric routing or packet loss.
What does TCP do to alleviate issues caused by out-of-order packets? - ANSWER TCP tries to
alleviate out-of-order issues by using sequence numbers, thus the receiver can reorder the
packets.
What could initiate the Fast Retransmit algorithm? - ANSWER The *Fast Retransmit* algorithm
could be initiated in the case of the receiver sending out duplicate ACKs, which generally
happens during packet arrival out-of-order.
What is the Fast Retransmit algorithm? ANSWER *Fast Retransmit* algorithm, once invoked,
has the sender retransmit sequences as the sender is assuming packet loss. This also has the
consequence of reduced window size and TCP throughput.
What is asymmetric routing? - ANSWER When the return path is different than the original path
of a packet. This isn't typically an issue unless mechanisms are in place to drop the data such
as NAT, Firewalls, and Unicast RPF.
What is ICMP Unreachable (Type-3)? - ANSWER *ICMP Unreachable (Type-3)* is a feedback
mechanism to notify the host about an unreachable destination. It is up to the sender to act
upon that information from the router. Usually, it's disabled by default, due to security reasons.
What is ICMP Unreachable (Type-3) Code-0? - ANSWER *ICMP Unreachable (Type-3) Code-0*
, is "Network Unreachable". This means there is no route to the network in question.
What is ICMP Unreachable (Type-3) Code-1? - ANSWER *ICMP Unreachable (Type-3) Code-1* is
"Host Unreachable". This means the host does not exist on the subnet.
What is ICMP Unreachable (Type-3) Code-2? - ANSWER *ICMP Unreachable (Type-3) Code-2* is
"Protocol Unreachable". This means an unknown protocol destined to the router,
What is ICMP Unreachable (Type-3) Code-3? - ANSWER *ICMP Unreachable (Type-3) Code-3* is
"Port Unreachable". This is due to a closed TCP/UDP port.
What is ICMP Unreachable (Type-3) Code-4? - ANSWER *ICMP Unreachable (Type-3) Code-4*
is "Fragmentation required and DF bit set".This results in data dropping on the router.
What is ICMP Unreachable (Type-3) Code-5? - ANSWER *ICMP Unreachable (Type-3) Code-5*
is "Source Route Failed".
What is ICMP Redirect Type-5? - ANSWER *ICMP Redirect Type-5* In the event that a packet
sent to a certain destination gateway, which is not the preferred gateway, is then forwarded to
the preferred gateway, a redirect message is sent to the sender of the packet indicating the
redirect and suggesting the use of the preferred gateway in the future.
What happens if the payload of an IP packet is greater than the MTU of the link? ANSWER When
payload > MTU, fragmentation must occur or else the data will be dropped. In IPv4,
fragmentation will occur unless DF bit is set.
How does IPv6 deal with potential Fragmentation problems? - ANSWER *Fragmentation*
issues are handled by the IPv6 source host it fragments IPv6 packets by using *Extension
Headers*.
What two ways can IPv6 packets prevent fragmentation? - ANSWER IPv6 packets avoid
fragmentation either by utilizing *Path MTU Discovery* (PMD) to determine lowest MTU on the
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