[Free] 2019(Nov) EnsurePass Cisco 300-115 Dumps with VCE and PDF 111-120

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Question No.111

Which command is needed to enable DHCP snooping if a switchport is connected to a DHCP server?

  1. ip dhcp snooping trust

  2. ip dhcp snooping

  3. ip dhcp trust

  4. ip dhcp snooping information

Correct Answer: A


When configuring DHCP snooping, follow these guidelines:

DHCP snooping is not active until you enable the feature on at least one VLAN, and enable DHCP globally on the switch.

Before globally enabling DHCP snooping on the switch, make sure that the devices acting as the DHCP server and the DHCP relay agent are configured and enabled.

If a Layer 2 LAN port is connected to a DHCP server, configure the port as trusted by entering the quot;ip dhcp snooping trustquot; interface configuration command.

If a Layer 2 LAN port is connected to a DHCP client, configure the port as untrusted by entering the no ip dhcp snooping trust interface configuration command.

Reference: http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst6500/ios/12- 2SX/configuration/guide/book/snoodhcp.html

Question No.112

Which AAA Authorization type includes PPP, SLIP, and ARAP connections?

  1. network

  2. IP mobile

  3. EXEC

  4. auth-proxy

Correct Answer: A


Method lists for authorization define the ways that authorization will be performed and the sequence in which these methods will be performed. A method list is simply a named list describing the authorization methods to be queried (such as RADIUS or TACACS ), in sequence. Method lists enable you to designate one or more security protocols to be used for authorization, thus ensuring a backup system in case the initial method fails. Cisco IOS software uses the first method listed to authorize users for specific network services; if that method fails to respond, the Cisco IOS software selects the next method listed in the method list. This process continues until there is successful communication with a listed authorization method, or all methods defined are exhausted. Method lists are specific to the authorization type requested:

Auth-proxyApplies specific security policies on a per-user basis. For detailed information on the authentication proxy feature, refer to the chapter quot;Configuring Authentication Proxyquot; in the quot;Traffic Filtering and Firewallsquot; part of this book.

CommandsApplies to the EXEC mode commands a user issues. Command authorization attempts authorization for all EXEC mode commands, including global configuration commands, associated with a specific privilege level.

EXECApplies to the attributes associated with a user EXEC terminal session.

NetworkApplies to network connections. This can include a PPP, SLIP, or ARAP connection. Reverse AccessApplies to reverse Telnet sessions. When you create a named method list, you are defining a particular list of authorization methods for the indicated authorization type.

Reference: http://www.cisco.com/c/en/us/td/docs/ios/12_2/security/configuration/guide/fsecur_c/scfathor.html

Question No.113

Which switch feature prevents traffic on a LAN from being overwhelmed by continuous multicast or broadcast traffic?

  1. storm control

  2. port security

  3. VTP pruning

  4. VLAN trunking

Correct Answer: A


A traffic storm occurs when packets flood the LAN, which creates excessive traffic and degrades network performance. The traffic storm control feature prevents LAN ports from being disrupted by a broadcast, multicast, or unicast traffic storm on physical interfaces from either mistakes in network configurations or from users issuing a DoS attack.

Reference: http://3c3cc.com/c/en/us/td/docs/routers/7600/ios/122SR/configuration/guide/sw cg/dos.pdf

Question No.114

When IP Source Guard with source IP filtering is enabled on an interface, which feature must be enabled on the access VLAN for that interface?

  1. DHCP snooping

  2. storm control

  3. spanning-tree portfast

  4. private VLAN

Correct Answer: A


IP Source Guard Configuration Guidelines

You can configure static IP bindings only on nonrouted ports. If you enter the ip source binding mac-address vlan vlan-id ip-address interface interface-id global configuration command on a routed interface, this error message appears:

Static IP source binding can only be configured on switch port.

When IP source guard with source IP filtering is enabled on an interface, DHCP snooping must be enabled on the access VLAN for that interface.

If you are enabling IP source guard on a trunk interface with multiple VLANs and DHCP snooping is enabled on all the VLANs, the source IP address filter is applied on all the VLANs.

You can enable this feature when 802.1x port-based authentication is enabled. Reference: http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst2960x/software/15- 0_2_EX/security/configuration_guide/b_sec_152ex_2960-x_cg/b_sec_152ex_2960- x_cg_chapter_01110.html

Question No.115

The command storm-control broadcast level 75 65 is configured under the switch port connected to the corporate mail server. In which three ways does this command impact the traffic? (Choose three.)

  1. SNMP traps are sent by default when broadcast traffic reaches 65% of the lower-level threshold.

  2. The switchport is disabled when unicast traffic reaches 75% of the total interface bandwidth.

  3. The switch resumes forwarding broadcasts when they are below 65% of bandwidth.

  4. Only broadcast traffic is limited by this particular storm control configuration.

  5. Multicast traffic is dropped at 65% and broadcast traffic is dropped at 75% of the total interface bandwidth.

  6. The switch drops broadcasts when they reach 75% of bandwidth.

Correct Answer: CDF


storm-control{broadcast|multicast|unicast}level{level[level-low] |ppspps[pps-low]}

Configure broadcast, multicast, or unicast storm control. By default, storm control is disabled. The keywords have these meanings:

For level, specify the rising threshold level for broadcast, multicast, or unicast traffic as a percentage (up to two decimal places) of the bandwidth. The port blocks traffic when the rising threshold is reached. The range is 0.00 to 100.00.

(Optional) For level-low, specify the falling threshold level as a percentage (up to two decimal places) of the bandwidth. This value must be less than or equal to the rising suppression value. The port forwards traffic when traffic drops below this level. If you do not configure a falling suppression level, it is set to the rising suppression level. The range is 0.00 to 100.00.

In this case, the broadcast keyword was used so only broadcast traffic is limited.

Reference: http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3550/software/release/12- 2_25_see/configuration/guide/3550SCG/swtrafc.html

Question No.116

Which private VLAN can have only one VLAN and be a secondary VLAN that carries unidirectional traffic upstream from the hosts toward the promiscuous ports and the gateway?

  1. isolated VLAN

  2. primary VLAN

  3. community VLAN

  4. promiscuous VLAN

Correct Answer: A


Understanding Primary, Isolated, and Community Private VLANs Primary VLANs and the two

types of secondary VLANs (isolated and community) have these characteristics:

Primary VLAN The primary VLAN carries traffic from the promiscuous ports to the host ports, both isolated and community, and to other promiscuous ports.

Isolated VLAN An isolated VLAN is a secondary VLAN that carries unidirectional traffic upstream from the hosts toward the promiscuous ports.You can configure multiple isolated VLANs in a private VLAN domain; all the traffic remains isolated within each one. Each isolated VLAN can have several isolated ports, and the traffic from each isolated port also remains completely separate.

Community VLANA community VLAN is a secondary VLAN that carries upstream traffic from the community ports to the promiscuous port and to other host ports in the same community. You can configure multiple community VLANs in a private VLAN domain. The ports within one community can communicate, but these ports cannot communicate with ports in any other community or isolated VLAN in the private VLAN.

Reference: http://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus5000/sw/configuration/guide/cli/C LIConfigurationGuide/PrivateVLANs.html

Question No.117

Refer to the exhibit. When a network administrator is attempting an SSH connection to the device, in which order does the device check the login credentials?


  1. RADIUS server, local username, line password

  2. RADIUS server, line password, local username

  3. Line password, local username, RADIUS server

  4. Line password, RADIUS server, local username

Correct Answer: A


SSH sessions use the vty lines, where the configured authentication method is named quot;default.quot; The AAA default login preference is stated in order from first to last, so here the quot;aaa authentication login default group radius local linequot; means to use RADIUS first, then if that fails use the local user database. Finally, if that fails use the line password.

Question No.118

A server with a statically assigned IP address is attached to a switch that is provisioned for DHCP snooping. For more protection against malicious attacks, the network team is considering enabling dynamic ARP inspection alongside DHCP snooping. Which solution ensures that the server maintains network reachability in the future?

  1. Disable DHCP snooping information option.

  2. Configure a static DHCP snooping binding entry on the switch.

  3. Trust the interface that is connected to the server with the ip dhcp snooping trust command.

  4. Verify the source MAC address of all untrusted interfaces with ip dhcp snooping verify mac- address command.

Correct Answer: B


Dynamic ARP inspection is a security feature that validates ARP packets in a network. It intercepts, logs, and discards ARP packets with invalid IP-to-MAC address bindings. This capability protects the network from certain man-in-the-middle attacks. Dynamic ARP inspection ensures that only valid ARP requests and responses are relayed.

The switch performs these activities:

Intercepts all ARP requests and responses on untrusted ports

Verifies that each of these intercepted packets has a valid IP-to-MAC address binding before updating the local ARP cache or before forwarding the packet to the appropriate destination. Drops invalid ARP packets

Dynamic ARP inspection determines the validity of an ARP packet based on valid IP-to- MAC address bindings stored in a trusted database, the DHCP snooping binding database. This database is built by DHCP snooping if DHCP snooping is enabled on the VLANs and on the switch. If the ARP packet is received on a trusted interface, the switch forwards the packet without any checks. On untrusted interfaces, the switch forwards the packet only if it is valid. To ensure network reachability to the server, configure a static DHCP snooping binding entry on the switch.

Reference: http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3750/software/releas e/12- 2_55_se/configuration/guide/scg3750/swdynarp.html

Question No.119

Which command would a network engineer apply to error-disable a switchport when a packet- storm is detected?

  1. router(config-if)#storm-control action shutdown

  2. router(config-if)#storm-control action trap

  3. router(config-if)#storm-control action error

  4. router(config-if)#storm-control action enable

Correct Answer: A


Configuring the Traffic Storm Control Shutdown Mode

To configure the traffic storm control shutdown mode on an interface, perform this task:

Command Purpose Step 1

Router(config)#interface{{type1 slot/port} | {port-channelnumber}} Selects an interface to configure.

Step 2

Router(config-if)#storm-control actionshutdown

(Optional) Configures traffic storm control to error-disable ports when a traffic storm occurs. Enter theno storm-control action shutdowncommand to revert to the default action (drop). Use the error disable detection and recovery feature, or theshutdownandno shutdown commands to reenable ports.

Reference: http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst6500/ios/12- 2SX/configuration/guide/book/storm.html

Question No.120

A DHCP configured router is connected directly to a switch that has been provisioned with DHCP snooping. IP Source Guard with the ip verify source port-security command is configured under the interfaces that connect to all DHCP clients on the switch. However, clients are not receiving an IP address via the DHCP server. Which option is the cause of this issue?

  1. The DHCP server does not support information option 82.

  2. The DHCP client interfaces have storm control configured.

  3. Static DHCP bindings are not configured on the switch.

  4. DHCP snooping must be enabled on all VLANs, even if they are not utilized for dynamic address allocation.

Correct Answer: A


When you enable both IP Source Guard and Port Security, using the ip verify source port- security interface configuration command, there are two caveats:

The DHCP server must support option 82, or the client is not assigned an IP address.

The MAC address in the DHCP packet is not learned as a secure address. The MAC address of the DHCP client is learned as a secure address only when the switch receives non-DHCP data traffic.

Reference: http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3550/software/releas e/12- 2_25_see/configuration/guide/3550SCG/swdhcp82.html#wp1069615

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