Cisco 300-101 Free Practice Questions

Answer: C 

Explanation: 

NetFlow Flows Key Fields

A network flow is identified as a unidirectional stream of packets between a given source and destination--

both are defined by a network-layer IP address and

transport-layer source and destination port numbers. Specifically, a flow is identified as the combination of

the following key fields:

Source IP address

Destination IP address

Source Layer 4 port number

Destination Layer 4 port number

Layer 3 protocol type

Type of service (ToS)

Input logical interface Reference: http://www.cisco.com/en/US/docs/ios-xml/ios/netflow/configuration/12-4t/

cfg-nflow- data-expt.html

Answer: A 

Explanation: 

Flow monitors are the NetFlow component that is applied to interfaces to perform network

traffic monitoring. Flow monitors consist of a record and a cache. You add the record to the flow monitor

after you create the flow monitor. The flow monitor cache is automatically created at the time the flow

monitor is applied to the first interface. Flow data is collected from the network traffic during the monitoring

process based on the key and nonkey fields in the record, which is configured for the flow monitor and

stored in the flow monitor cache. Reference: http://www.cisco.com/c/en/us/td/docs/ios/fnetflow/command/

reference/fnf_book/fnf_01.html#w p1314030

Answer: C 

Explanation: 

Configuration Examples for IP SLAs TCP Connect Operations The following example shows

how to configure a TCP Connection-oriented operation from Device B to the Telnet port (TCP port 23) of IP

Host 1 (IP address 10.0.0.1), as shown in the "TCP Connect Operation" figure in the "Information About

the IP SLAs TCP Connect Operation" section. The operation is scheduled to start immediately. In this

example, the control protocol is disabled on the source (Device B). IP SLAs uses the control protocol to

notify the IP SLAs responder to enable the target port temporarily. This action allows the responder to reply

to the TCP Connect operation. In this example, because the target is not a Cisco device and a well- known

TCP port is used, there is no need to send the control message. Device A (target device) Configuration

configure terminal ip sla responder tcp-connect ipaddress 10.0.0.1 port 23 

Reference: http://

www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipsla/configuration/15-mt/sla-15- mt-book/ sla_tcp_conn.html

Answer: A 

Explanation: 

Enabling Flow-Label Marking in Packets that Originate from the Device This feature allows the device to

track destinations to which the device has sent packets that

are 1280 bytes or larger.

SUMMARY STEPS

1.enable

2.configure terminal

3.ipv6 flowset

4.exit

5.clear ipv6 mtu

DETAILED STEPS

Command or Action Purpose

Step 1 enable Enables privileged EXEC mode.

Enter your password if prompted.

Example:

Device> enable

Step 2 configure terminal Enters global configuration mode.

Example:

Device# configure

terminal

Step 3 ipv6 flowset Configures flow-label marking in 1280-byte or larger packets sent by the device.

Example:

Device# configure

terminal

Step 3 ipv6 flowset Configures flow-label marking in 1280-byte or larger packets sent by the device.

Example:

Device(config)# ipv6

flowset

Reference: http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipv6_basic/configuration/15- mt/ip6b-15-mtbook/ip6-mtu-path-disc.html

Answer: A 

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 an EUI-48 MAC address. Here is an example showing how

a 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.

Once the above is done, we have a fully functional EUI-64 format address. 

Reference: https://

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

Answer: C 

Explanation: 

The private IP address ranges defined in RFC 1918 are as follows:

10.0.0.0 - 10.255.255.255

172.16.0.0 - 172.31.255.255

192.168.0.0 - 192.168.255.255 

These IP addresses should never be allowed from external networks into a

corporate network as they would only be able to reach the network from the outside via routing problems or

if the IP addresses were spoofed. This ACL is used to prevent all packets with a spoofed reserved private

source IP address to enter the network. The log keyword also enables logging of this intrusion attempt.

Answer: C 

Explanation: 

Answer: C 

Explanation: 

The 0.0.0.0/0 route is the default route and is listed as the first CEF entry. Here we see the next hop for this default route lists 192.168.201.1 as the default router (gateway of last resort).

Answer: B 

Explanation: 

Answer: B 

Explanation: 

Answer: A 

Explanation: 

Answer: A 

Explanation: 

To let a router forward broadcast packet the command ip helper-address can be used. The broadcasts will

be forwarded to the unicast address which is specified with the ip helper command.

ip helper-address {ip address}

When configuring the ip helper-address command, the following broadcast packets will be forwarded by

the router by default:

TFTP - UDP port 69

Domain Name System (DNS) UDP port 53

Time service - port 37

NetBIOS Name Server - port 137

NetBIOS Datagram Server - port 138

Bootstrap Protocol (BOOTP) - port 67

TACACS UDP port 49 Reference: http://www.cisco-faq.com/163/forward_udp_broadcas.html

Topic 6, Infrastructure Services 

61. A network engineer is configuring SNMP on network devices to utilize one-way SNMP notifications. However, the engineer is not concerned with authentication or encryption. Which command satisfies the requirements of this scenario? 

A. router(config)#snmp-server host 172.16.201.28 traps version 2c CISCORO 

B. router(config)#snmp-server host 172.16.201.28 informs version 2c CISCORO 

C. router(config)#snmp-server host 172.16.201.28 traps version 3 auth CISCORO 

D. router(config)#snmp-server host 172.16.201.28 informs version 3 auth CISCORO 

Answer: B 

Explanation: 

When a router crashes, it is sometimes useful to obtain a full copy of the memory image (called a core

dump) to identify the cause of the crash. Core dumps are generally very useful to your technical support representative.

Four basic ways exist for setting up the router to generate a core dump:

Using Trivial File Transfer Protocol (TFTP)

Using File Transfer Protocol (FTP)

Using remote copy protocol (rcp)

Using a Flash disk Reference: http://www.cisco.com/en/US/docs/internetworking/troubleshooting/guide/

tr19aa.html

Answer: A,B,C 

Explanation: 

show crypto ipsec sa This command shows IPsec SAs built between peers. The encrypted

tunnel is built between 12.1.1.1 and 12.1.1.2 for traffic that goes between networks 20.1.1.0 and 10.1.1.0.

You can see the two Encapsulating Security Payload (ESP) SAs built inbound and outbound.

Authentication Header (AH) is not used since there are

no AH SAs.

This output shows an example of the show crypto ipsec sa command (bolded ones found in answers for

this question).

interface: FastEthernet0

Crypto map tag: test, local addr. 12.1.1.1

local ident (addr/mask/prot/port): (20.1.1.0/255.255.255.0/0/0) remote ident (addr/mask/prot/port):

(10.1.1.0/255.255.255.0/0/0) current_peer: 12.1.1.2

PERMIT, flags={origin_is_acl,}

#pkts encaps: 7767918, #pkts encrypt: 7767918, #pkts digest 7767918 #pkts decaps: 7760382, #pkts

decrypt: 7760382, #pkts verify 7760382 #pkts compressed:

0, #pkts decompressed: 0

#pkts not compressed: 0, #pkts compr. failed: 0,

#pkts decompress failed: 0, #send errors 1, #recv errors 0 local crypto endpt.: 12.1.1.1, remote crypto

endpt.: 12.1.1.2 path mtu 1500, media mtu 1500

current outbound spi: 3D3

inbound esp sas:

spi: 0x136A010F(325714191)

transform: esp-3des esp-md5-hmac ,

in use settings ={Tunnel, }

slot: 0, conn id: 3442, flow_id: 1443, crypto map: test sa timing: remaining key lifetime (k/sec):

(4608000/52) IV size: 8 bytes

replay detection support: Y

inbound ah sas:

inbound pcp sas:

inbound pcp sas:

outbound esp sas:

spi: 0x3D3(979)

transform: esp-3des esp-md5-hmac ,

in use settings ={Tunnel, }

slot: 0, conn id: 3443, flow_id: 1444, crypto map: test sa timing: remaining key lifetime (k/sec):

(4608000/52) IV size: 8 bytes

replay detection support: Y

outbound ah sas:

outbound pcp sas:

Reference: http://www.cisco.com/c/en/us/support/docs/security-vpn/ipsec-negotiation-ike- protocols/5409-

ipsec-debug-00.html

Answer: Here is the solution below: 

Explanation: 

To troubleshoot the problem, first issue the show running-config on all of 4 routers. Pay more attention to the outputs of routers R2 and R3 The output of the "show running-config" command of R2: 

The output of the "show running-config" command of R3: 

We knew that all areas in an Open Shortest Path First (OSPF) autonomous system must be physically connected to the backbone area (Area 0). In some cases, where this is not possible, we can use a virtual link to connect to the backbone through a non-backbone area. The area through which you configure the virtual link is known as a transit area. In this case, the area 11 will become the transit area. Therefore, routers R2 and R3 must be configured with the area <area id> virtual-link <neighbor router-id>command. + Configure virtual link on R2 (from the first output above, we learned that the OSPF process ID of R2 is 1): 

R2>enable 

R2#configure terminal 

R2(config)#ipv6 router ospf 1 

R2(config-rtr)#area 11 virtual-link 3.3.3.3 

Save the configuration: 

R2(config-rtr)#end 

R2#copy running-config startup-config 

(Notice that we have to use neighbor router-id 3.3.3.3, not R2's router-id 2.2.2.2) + Configure virtual link on R3 (from the second output above, we learned that the OSPF process ID of R3 is 1 and we have to disable the wrong configuration of "area 54 virtual-link 4.4.4.4"): 

R3>enable 

R3#configure terminal 

R3(config)#ipv6 router ospf 1 

R3(config-rtr)#no area 54 virtual-link 4.4.4.4 

R3(config-rtr)#area 11 virtual-link 2.2.2.2 

Save the configuration: 

R3(config-rtr)#end 

R3#copy running-config startup-config 

You should check the configuration of R4, too. Make sure to remove the incorrect configuration statements to get the full points. 

R4(config)#ipv6 router ospf 1 

R4(config-router)#no area 54 virtual-link 3.3.3.3 

R4(config-router)#end 

After finishing the configuration doesn’t forget to ping between R1 and R4 to make sure they work. 

Note. If you want to check the routing information, use the show ipv6 route command, not "show ip route". 

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