100-150 Practice Test 21 — 15 Questions

Question 1

An endpoint is experiencing high latency and jitter during a VoIP call, but data traffic remains stable. Which QoS mechanism should be verified on the local switch port to ensure voice media frames are prioritized correctly?

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

Verify the ingress port trust state is configured for DSCP or CoS.. Voice traffic is highly sensitive to delay, jitter, and packet loss. Prioritizing voice packets via Class of Service or Differentiated Services Code Point (DSCP) tagging ensures that these frames bypass standard data queues. Verifying the trust state on the access port is critical, as it confirms the switch honors the classification assigned by the endpoint, preventing the media traffic from being relegated to the best-effort queue.

Answer

Enable port-security on the voice VLAN.

Answer

Increase the maximum transmission unit size on the interface.

Answer

Disable Spanning Tree Protocol on the voice port.

Question 2

A network engineer is comparing TCP and UDP for a new application that streams live video to many users. The application can tolerate some packet loss but requires low latency. The engineer wants to choose the transport protocol and configure it appropriately. Which two characteristics describe UDP in this scenario? (Choose two.)

Accepted Answer

UDP provides a connectionless service, so it does not establish a session before sending data, reducing latency.. UDP is connectionless, so it avoids handshake delay, and its header is only 8 bytes, reducing overhead compared to TCP. These traits make UDP suitable for live video where low latency is more important than reliability. The application can tolerate some loss, so the absence of retransmission and in-order delivery is acceptable.

Answer

UDP guarantees in-order delivery of packets, ensuring video frames are displayed correctly.

Answer

UDP uses a sliding window mechanism to ensure reliable delivery of all video frames.

Answer

UDP performs congestion control to avoid overwhelming the network, which is essential for streaming to many users.

Question 3

A network technician is configuring a new Cisco switch for a small business. The technician needs to ensure that the switch can be managed remotely from a different subnet. Which TWO configurations are required to enable remote management access? (Choose two.)

Accepted Answer

Assign an IP address to a VLAN interface (SVI).. Remote management of a switch from a different subnet requires an IP address assigned to an SVI for network reachability, and a default gateway so the switch can route management traffic off its local subnet. These two configurations provide the necessary Layer 3 connectivity for protocols like SSH or Telnet.

Answer

Enable CDP on all interfaces.

Answer

Set the switch to transparent VTP mode.

Answer

Configure port security on the management interface.

Question 4

A security team wants to protect users who connect laptops to the corporate wireless network from attackers who set up a nearby access point broadcasting the same SSID with a stronger signal. The requirement is that clients authenticate the network before associating and that the credentials never traverse the wireless medium in a recoverable form. Which technology satisfies these requirements?

Accepted Answer

WPA2-Enterprise with 802.1X and EAP-TLS. Mutual authentication and protection of credentials over the air are satisfied by WPA2-Enterprise with 802.1X and EAP-TLS. The client verifies the RADIUS server certificate before proceeding, which exposes a rogue access point that cannot present a trusted certificate, and certificate-based authentication avoids transmitting a reusable secret. Personal mode, open authentication, and WEP all lack server-side authentication.

Answer

WEP with a 128-bit shared key

Answer

Open authentication with a captive portal

Answer

WPA2-Personal with a pre-shared key

Question 5

A small branch office has been assigned the network 192.168.50.0/24. The network administrator must divide it into four equal-sized subnets to match four separate departments. Which subnet mask should be configured on the router interfaces to create exactly four usable subnets?

Accepted Answer

255.255.255.192. To create four equal subnets from a single /24 block, two host bits must be borrowed, converting the prefix to /26. The resulting mask 255.255.255.192 divides the 192.168.50.0 range into four blocks of 64 addresses each, providing 62 usable host addresses per department. Masks that borrow fewer bits yield too few subnets, while borrowing more bits creates excess subnets with reduced host capacity.

Answer

255.255.255.240

Answer

255.255.255.224

Answer

255.255.255.128

Question 6

A network administrator at a small clinic wants to prevent unauthorized users from plugging a personal laptop into an unused wall jack in the waiting room and obtaining an IP address on the internal VLAN. The clinic uses a Cisco Catalyst switch with 802.1X-capable access ports and a RADIUS server. Which solution best meets this requirement?

Accepted Answer

Configure 802.1X authentication on access ports so devices must authenticate to the RADIUS server before the port is authorized.. The clinic needs to stop unauthorized devices from gaining any network access through unused wall jacks. 802.1X enforces authentication at the switch port before any Layer 3 connectivity is granted, so a laptop without valid credentials cannot obtain an IP address on the internal VLAN. Port security, VLAN ACLs, and Dynamic ARP Inspection address different threats and do not authenticate the user or device identity.

Answer

Create a VLAN access control list that denies all traffic from the waiting-room VLAN to the internal VLAN.

Answer

Enable port security with a maximum of one MAC address and violation mode shutdown on all access ports.

Answer

Enable Dynamic ARP Inspection on the waiting-room VLAN to block ARP spoofing from unknown devices.

Question 7

An administrator is running UTP cabling near heavy machinery and fluorescent lights. Users report intermittent connectivity and slow speeds. What is the most likely cause of this issue?

Accepted Answer

EMI. EMI (electromagnetic interference) is the most likely cause because heavy machinery and fluorescent lights emit electromagnetic fields that induce noise on unshielded twisted-pair (UTP) cabling. This noise corrupts signals, causing intermittent connectivity, retransmissions, and slow speeds. UTP lacks the shielding that STP or fiber provides against such interference.

Answer

Crosstalk

Answer

Attenuation

Answer

Reflection

Question 8

A user reports that they cannot access any network resources, including the internet. A technician checks the user's workstation and finds that it has an IP address of 169.254.10.5 with a subnet mask of 255.255.0.0. The technician verifies that the switch port is active and the cable is connected. What is the most likely cause of the problem?

Accepted Answer

The workstation failed to obtain an IP address from a DHCP server.. An IP address in the 169.254.0.0/16 range is an APIPA address, automatically assigned when a DHCP server cannot be reached. This prevents normal network communication. The technician should investigate DHCP server availability, relay agent configuration, or physical connectivity to the DHCP server.

Answer

The workstation has a static IP address that conflicts with another device.

Answer

The default gateway is misconfigured on the workstation.

Answer

The DNS server is unreachable, preventing name resolution.

Question 9

Refer to the exhibit. Based on the JSON configuration for the switch port, what type of endpoint is most likely connected to this interface?

Accepted Answer

A Cisco IP Phone with a PC attached. Specific port configurations often reveal the type of endpoint connected. In this case, the presence of both a data VLAN and a voice VLAN, combined with the 'power_inline' setting, strongly indicates a device that handles both voice and data traffic while requiring power from the switch.

Answer

A high-speed network printer

Answer

A wireless access point in bridge mode

Answer

A server hosting virtual machines

Question 10

A network engineer is configuring a Cisco router interface that connects to an ISP. The ISP has assigned the engineer a single public IP address of 203.0.113.10 with a subnet mask of 255.255.255.252 and a default gateway of 203.0.113.9. The engineer needs to configure the router interface with the correct IP address and mask. Which configuration should be applied?

Accepted Answer

ip address 203.0.113.10 255.255.255.252. The ISP assigned a /30 subnet, so the correct mask is 255.255.255.252. Within 203.0.113.8/30, the usable host addresses are 203.0.113.9 and 203.0.113.10, and the gateway uses 203.0.113.9. The router interface must therefore be configured with 203.0.113.10 and the /30 mask to be in the same subnet as the ISP gateway and establish connectivity.

Answer

ip address 203.0.113.9 255.255.255.252

Answer

ip address 203.0.113.10 255.255.255.0

Answer

ip address 203.0.113.10 255.255.255.248

Question 11

A network administrator needs to connect two switches using a link that allows multiple VLANs to traverse a single physical path. Which configuration step is essential to ensure this functionality is enabled properly?

Accepted Answer

Configure the switch port mode to trunk.. To allow multiple VLANs across a single physical link, the ports must be configured as trunks using the 802.1Q encapsulation protocol. This process involves tagging frames to identify their originating VLAN. Understanding trunking is critical for scalable network design, as it eliminates the need for individual cables for every VLAN, thereby optimizing port density and simplifying cabling management across enterprise distribution and core layers.

Answer

Set the switch port mode to access and assign it to VLAN 1.

Answer

Configure the port as a static EtherChannel member.

Answer

Enable Spanning Tree Protocol on all interfaces.

Question 12

Which mechanism does the Spanning Tree Protocol (STP) use to detect and prevent Layer 2 loops in a network with redundant links?

Accepted Answer

Exchange of Bridge Protocol Data Units (BPDUs). STP prevents loops by designating certain redundant ports as 'blocked'. It uses Bridge Protocol Data Units (BPDUs) to communicate between switches, elect a Root Bridge, and calculate the shortest path to that root. By logically disabling redundant paths, STP ensures a loop-free topology while maintaining the ability to automatically restore connectivity if a primary link fails, providing essential resilience for switched LANs.

Answer

Broadcast storm suppression

Answer

Source MAC address learning

Answer

Packet TTL expiration

Question 13

Refer to the exhibit. An administrator observes that interface Gig0/1 is in 'up' status but experiences high latency and interface errors. Based on the provided configuration, what is the most likely cause?

Accepted Answer

The interface is set to auto-negotiate, causing a duplex mismatch.. An interface that is 'up' but shows high latency and errors typically indicates a duplex mismatch, which occurs when one side is hard-set to full duplex and the other auto-negotiates to half duplex. This causes collisions, late collisions, FCS errors, and degraded throughput. The exhibit's configuration showing auto-negotiation on one side and a fixed setting on the other confirms this scenario.

Answer

The cable is faulty.

Answer

The interface is administratively shut down.

Answer

The bandwidth is too low for traffic.

Question 14

A network technician is configuring a Cisco switch for a new VLAN. The technician wants to verify that the VLAN has been created and is active, and also see which ports are assigned to it. Which command should the technician use?

Accepted Answer

show vlan brief. The 'show vlan brief' command provides a concise list of all VLANs, their status, and the ports assigned to each. This directly answers the technician's need to verify VLAN creation and port membership. Other commands like 'show interfaces status' or 'show running-config' provide related but less direct or complete information.

Answer

show mac address-table

Answer

show running-config

Answer

show interfaces status

Question 15

Which TWO of the following statements correctly describe the characteristics of IPv4 address classes?

Accepted Answer

Class A addresses begin with a binary 0 in the first octet.. Understanding classful boundaries is historical but necessary for identifying legacy network structures and subnetting fundamentals. Class A uses the first octet for network identification with a leading 0, while Class C uses three octets for the network portion with a leading 110. This knowledge assists in recognizing address ranges and identifying potential overlaps in misconfigured legacy network environments.

Answer

Class B addresses use the first 24 bits for the network portion.

Answer

Class D addresses are reserved for private internal usage.

Answer

Class E addresses are used for public internet routing.