All About Free 300-101 braindumps

Answer: C 

Explanation: 

Answer: D 

Explanation: 

Access list 2 is more specific, allowing only 1.2.3.0/24, whereas access list 1 permits all 1.0.0.0/8

networks. This question also asks us to apply this distribute list only to the outbound direction of the fast Ethernet 0/0 interface, so the correct command is "distribute list 2

out FastEthernet0/0."

Answer: D 

Explanation: 

PAP authentication involves a two-way handshake where the username and password are

sent across the link in clear text; hence, PAP authentication does not provide any protection against

playback and line sniffing. CHAP authentication, on the other hand, periodically verifies the identity of the

remote node using a three-way handshake. After the PPP link is established, the host sends a "challenge"

message to the remote node. The remote node responds with a value calculated using a one-way hash

function. The host checks the response against its own calculation of the expected hash value. If the

values match, the authentication is acknowledged; otherwise, the connection is terminated. Reference:

http://www.cisco.com/c/en/us/support/docs/wan/point-to-point-protocol-ppp/10241- ppp-callinhostname.

html

Answer: A 

Explanation: 

We came across a recent issue where a user setup a router for NetFlow export but was unable to see the

OUT traffic for the interfaces in NetFlow Analyzer. Every NetFlow configuration aspect was checked and

nothing incorrect was found. That is when we noticed the `no ip cef' command on the router. CEF was

enabled at the global level and within seconds, NetFlow Analyzer started showing OUT traffic for the

interfaces. This is why this topic is about Cisco Express Forwarding.

What is switching?

A Router must make decisions about where to forward the packets passing through. This decision-making

process is called "switching". Switching is what a router does when it makes the following decisions:

1.Whether to forward or not forward the packets after checking that the destination for the packet is

reachable.

2.If the destination is reachable, what is the next hop of the router and which interface will the router use to

get to that destination.

What is CEF?

CEF is one of the available switching options for Cisco routers. Based on the routing table, CEF creates its

own table, called the Forwarding Information Base (FIB). The FIB is organized differently than the routing

table and CEF uses the FIB to decide which interface to send traffic from. CEF offers the following

benefits:

1.Better performance than fast-switching (the default) and takes less CPU to perform the same task.

2.When enabled, allows for advanced features like NBAR

3.Overall, CEF can switch traffic faster than route-caching using fast-switching

How to enable CEF?

CEF is disabled by default on all routers except the 7xxx series routers. Enabling and Disabling CEF is

easy. To enable CEF, go into global configuration mode and

enter the CEF command.

Router# config t

Router(config)# ip cef

Router(config)#

To disable CEF, simply use the `no' form of the command, ie. `no ip cef`.

Why CEF Needed when enabling NetFlow ?

CEF is a prerequisite to enable NetFlow on the router interfaces. CEF decides through which interface

traffic is exiting the router. Any NetFlow analyzer product will calculate the OUT traffic for an interface

based on the Destination Interface value present in the NetFlow packets exported from the router. If the

CEF is disabled on the router, the NetFlow packets exported from the router will have "Destination

interface" as "null" and this leads NetFlow Analyzer to show no OUT traffic for the interfaces. Without

enabling the CEF on the router, the NetFlow packets did not mark the destination interfaces and so

NetFlow Analyzer was not able to show the OUT traffic for the interfaces. Reference: https://

blogs.manageengine.com/network-2/netflowanalyzer/2010/05/19/need-for-cef- in-netflow-data-export.html

Answer: A 

Explanation: 

Network administrators can use Unicast Reverse Path Forwarding (Unicast RPF) to help limit

the malicious traffic on an enterprise network. This security feature works by enabling a router to verify the

reachability of the source address in packets being forwarded. This capability can limit the appearance of

spoofed addresses on a network. If the source IP address is not valid, the packet is discarded. Unicast

RPF works in one of three different modes: strict mode, loose mode, or VRF mode. Note that not all

network devices support all three modes of operation. Unicast RPF in VRF mode will not be covered in this

document. When administrators use Unicast RPF in strict mode, the packet must be received on the

interface that the router would use to forward the return packet. Unicast RPF configured in strict mode may

drop legitimate traffic that is received on an interface that was not the router's choice for sending return

traffic. Dropping this legitimate traffic could occur when asymmetric routing paths are present in the

network. When administrators use Unicast RPF in loose mode, the source address must appear in the

routing table. Administrators can change this behavior using the allow-default option, which allows the use

of the default route in the source verification process. Additionally, a packet that contains a source address

for which the return route points to the Null 0 interface will be dropped. An access list may also be

specified that permits or denies certain source addresses in Unicast RPF loose mode. Care must be taken

to ensure that the appropriate Unicast RPF mode (loose or strict) is configured during the deployment of

this feature because it can drop legitimate traffic. Although asymmetric traffic flows may be of concern

when deploying this feature, Unicast RPF loose mode is a scalable option for networks that contain

asymmetric routing paths. Reference: http://www.cisco.com/web/about/security/intelligence/unicastrpf.

html

Answer: A 

Explanation: 

To display information about the Cisco Express Forwarding adjacency table or the hardware Layer 3-

switching adjacency table, use the show adjacency command.

Reasons for Incomplete Adjacencies

There are two known reasons for an incomplete adjacency:

The router cannot use ARP successfully for the next-hop interface.

After a clear ip arp or a clear adjacency command, the router marks the adjacency as incomplete. Then it

fails to clear the entry.

In an MPLS environment, IP CEF should be enabeled for Label Switching. Interface level command ip

route-cache cef No ARP Entry When CEF cannot locate a valid adjacency for a destination prefix, it punts

the packets to the CPU for ARP resolution and, in turn, for completion of the adjacency.

Reference: http://www.cisco.com/c/en/us/support/docs/ip/express-forwarding-cef/17812-cefincomp.

html#t4

Answer: A 

Explanation: 

Explanation: Extended Unique Identifier (EUI), as per RFC2373, allows a host to assign iteslf a unique 64-

Bit IP Version 6 interface identifier (EUI-64). This feature is a key benefit over IPv4 as it eliminates the

need of manual configuration or DHCP as in the world of IPv4. The IPv6 EUI-64 format address is obtained

through the 48-bit MAC address. The Mac address is first separated into two 24-bits, with one being OUI

(Organizationally Unique Identifier) and the other being NIC specific. The 16-bit 0xFFFE is then inserted

between these two 24-bits to for the 64-bit EUI address. IEEE has chosen FFFE as a reserved value which

can only appear in EUI-64 generated from the EUI-48 MAC address. Here is an example showing how the

Mac Address is used to generate EUI.

Next, the seventh bit from the left, or the universal/local (U/L) bit, needs to be inverted. This bit identifies

whether this interface identifier is universally or locally administered. If 0, the address is locally

administered and if 1, the address is globally unique. It is worth noticing that in the OUI portion, the globally

unique addresses assigned by the IEEE has always been set to 0 whereas the locally created addresses

has 1 configured. Therefore, when the bit is inverted, it maintains its original scope (global unique address

is still global unique and vice versa). The reason for inverting can be found in RFC4291 section 2.5.1.

Reference: https:// supportforums.cisco.com/document/100566/understanding-ipv6-eui-64-bit- address

Answer: A 

Explanation: 

The sampling mode determines the algorithm that selects a subset of traffic for NetFlow

processing. In the random sampling mode that Random Sampled NetFlow uses, incoming packets are

randomly selected so that one out of each n sequential packets is selected on average for NetFlow

processing. For example, if you set the sampling rate to 1 out of 100 packets, then NetFlow might sample

the 5th, 120th, 199th, 302nd, and so on packets. This sample configuration provides NetFlow data on 1

percent of total traffic. The n value is a parameter from 1 to 65535 packets that you can configure. Table 2

show flow-sampler Field Descriptions Field Description Sampler Name of the flow sampler id Unique ID of

the flow sampler packets matched Number of packets matched for the flow sampler mode Flow sampling

mode sampling interval is Flow sampling interval (in packets) Reference: http://www.cisco.com/c/en/us/td/

docs/ios/12_0s/feature/guide/nfstatsa.html#wp1084291

Answer: A 

Explanation: 

Restrictions for EVN

An EVN trunk is allowed on any interface that supports 802.1q encapsulation, such as Fast Ethernet,

Gigabit Ethernet, and port channels.

A single IP infrastructure can be virtualized to provide up to 32 virtual networks end-to-end.

If an EVN trunk is configured on an interface, you cannot configure VRF-Lite on the same interface.

OSPFv3 is not supported; OSPFv2 is supported.

Reference: 

http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/evn/configuration/xe-3s/evn-xe-3s- book/evnoverview.Pdf

Answer: A 

Explanation: 

Topic 4, VPN Technologies 

45. A company has just opened two remote branch offices that need to be connected to the corporate network. Which interface configuration output can be applied to the corporate router to allow communication to the remote sites? 

A. interface Tunnel0 

bandwidth 1536 

ip address 209.165.200.230 255.255.255.224 

tunnel source Serial0/0 

tunnel mode gre multipoint 

B. interface fa0/0 

bandwidth 1536 

ip address 209.165.200.230 255.255.255.224 

tunnel mode gre multipoint 

C. interface Tunnel0 

bandwidth 1536 

ip address 209.165.200.231 255.255.255.224 

tunnel source 209.165.201.1 

tunnel-mode dynamic 

D. interface fa 0/0 

bandwidth 1536 

ip address 209.165.200.231 255.255.255.224 

tunnel source 192.168.161.2 

tunnel destination 209.165.201.1 

tunnel-mode dynamic