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Question 141

Which TCP flag starts a connection establishment?

1. FIN
2. ACK
3. SYN
4. RST

Correct Answer: 3

Explanation:

The SYN flag is used by TCP to initiate a connection establishment process. During the TCP three-way handshake, the client typically sends a SYN, the server responds with SYN-ACK, and the client completes the exchange with ACK. FIN is associated with graceful connection termination, while RST indicates an abrupt reset. ACK confirms receipt of information. Understanding TCP flags is useful when analyzing packet captures and diagnosing connection-establishment problems between network applications.

Question 142

Which IPv4 subnet contains 62 usable hosts?

1. /26
2. /28
3. /29
4. /30

Correct Answer: 1

Explanation:

A /26 IPv4 subnet contains 64 total addresses. In a traditional subnet, one address identifies the network and another identifies the broadcast address, leaving 62 usable host addresses. A /28 provides 14 usable addresses, /29 provides 6, and /30 provides 2. Subnetting allows administrators to divide larger address spaces into appropriately sized networks. Selecting the correct prefix is important when allocating addresses to user segments, server networks, or point-to-point connections.

Question 143

Which Ethernet table entry maps a MAC address to a port?

1. Routing table
2. ARP table
3. MAC address table
4. DNS cache

Correct Answer: 3

Explanation:

A switch’s MAC address table associates learned destination MAC addresses with the switch ports through which those devices are reachable. When a frame arrives, the switch examines its destination MAC address and uses the table to determine where forwarding should occur. If the destination is unknown, the switch may flood the frame within the appropriate VLAN. The ARP table serves a different purpose by mapping IP addresses to Layer 2 addresses. Understanding both tables is important for troubleshooting local network forwarding.

Question 144

Which switch behavior occurs for an unknown unicast destination?

1. Drop immediately
2. Flood within VLAN
3. Route to gateway
4. Send to CPU

Correct Answer: 2

Explanation:

When a switch receives a frame whose destination MAC address is unknown, it normally floods the frame out relevant ports within the same VLAN, excluding the port on which the frame arrived. This allows the destination device to respond and enables the switch to learn the correct MAC address. The frame is not automatically routed to a gateway simply because its MAC address is unknown. VLAN boundaries still limit where the unknown unicast frame can be flooded.

Question 145

Which STP protocol provides faster topology convergence?

1. STP
2. MSTP
3. RSTP
4. PVST

Correct Answer: 3

Explanation:

RSTP, or Rapid Spanning Tree Protocol, provides faster convergence than traditional STP. It improves the transition behavior of ports and reduces the time required for the network to recover from certain topology changes. RSTP retains the fundamental loop-prevention purpose of spanning tree while introducing more efficient mechanisms for handling topology changes. MSTP extends spanning-tree operation by allowing multiple VLANs to be mapped into spanning-tree instances. Choosing an appropriate spanning-tree mode depends on the network design and compatibility requirements.

Question 146

Which switch technology groups several devices into one logical system?

1. Stacking
2. Mirroring
3. Filtering
4. Bridging

Correct Answer: 1

Explanation:

Switch stacking allows multiple compatible physical switches to operate as a unified logical system. This can simplify management and provide coordinated operation across the participating devices. Depending on the platform and design, stacking can also improve redundancy and simplify expansion. Stacking is different from link aggregation, which combines physical links into a logical connection. Administrators should ensure that participating switches support compatible stacking technologies and are configured according to the platform’s requirements.

Question 147

Which VLAN port type can support tagged and untagged traffic?

1. Access
2. Hybrid
3. Console
4. Loopback

Correct Answer: 2

Explanation:

A hybrid port can be configured to handle both tagged and untagged VLAN traffic according to its VLAN membership and tagging configuration. This flexibility makes hybrid ports useful in scenarios where different types of traffic must be handled through the same physical interface. Access ports are generally associated with a single untagged VLAN, while trunk ports are primarily designed to carry multiple VLANs using tags. Correct tagging behavior must be configured carefully to prevent VLAN traffic from being assigned incorrectly.

Question 148

Which ACL value identifies a wildcard matching pattern?

1. Subnet mask
2. Prefix length
3. Wildcard mask
4. Gateway address

Correct Answer: 3

Explanation:

A wildcard mask specifies which portions of an address should be considered when an ACL rule evaluates traffic. Unlike a conventional subnet mask, wildcard masks use matching logic that determines which bits must match and which bits can vary. This allows ACL rules to represent individual addresses, ranges, or groups of addresses efficiently. Administrators should carefully verify wildcard values because an incorrect mask can cause an ACL rule to match more or fewer addresses than intended.

Question 149

Which NAT feature allows external users to reach an internal server?

1. PAT
2. Easy IP
3. NAT server
4. Dynamic pool

Correct Answer: 3

Explanation:

A NAT server configuration can publish an internal service so that external users can reach it through a translated public address and service port. This is useful for exposing selected services such as web or application servers while keeping their internal addresses private. PAT is primarily used for sharing public addresses among internal clients, while dynamic NAT typically maps addresses from a pool. NAT server functionality therefore focuses on inbound access to internal resources through controlled translations.

Question 150

Which DHCP value specifies how long an address remains assigned?

1. Gateway
2. Lease time
3. DNS suffix
4. Server identifier

Correct Answer: 2

Explanation:

DHCP lease time determines how long a client can use an assigned IP address before it must renew the lease. During normal DHCP operation, clients can request renewal before the lease expires. Appropriate lease durations depend on the network environment. Shorter leases can allow addresses to be reclaimed more quickly in highly dynamic environments, while longer leases can reduce renewal traffic in stable networks. Understanding lease behavior helps administrators troubleshoot address allocation and unexpected changes in client addressing.

Question 151

Which TCP flag confirms received data?

1. ACK
2. SYN
3. FIN
4. PSH

Correct Answer: 1

Explanation:

The ACK flag indicates acknowledgment information in TCP communication. It allows a receiver to confirm that data or control information has been received and indicates the next expected sequence position. SYN is primarily associated with establishing a TCP connection, FIN is used for graceful termination, and PSH requests that buffered data be delivered promptly to the receiving application. TCP acknowledgment behavior is fundamental to reliable transport and is frequently examined during packet-level troubleshooting.

Question 152

Which Ethernet method detects frame errors using a checksum?

1. ARP
2. FCS
3. VLAN
4. PVID

Correct Answer: 2

Explanation:

The Frame Check Sequence, or FCS, is used in Ethernet frames to detect transmission errors. The receiving device can calculate the relevant value and compare it with the value contained in the frame. If the values do not match, the frame is considered corrupted and can be discarded. FCS helps identify errors occurring during transmission but does not correct them. When interface statistics show increasing error counts, administrators can investigate cabling, transceivers, interference, or other physical-layer conditions.

Question 153

Which wireless feature allows clients to move between APs?

1. Roaming
2. Bridging
3. Trunking
4. Flooding

Correct Answer: 1

Explanation:

Wireless roaming allows a client to move between access points while maintaining connectivity to the WLAN service. In a properly designed wireless network, neighboring APs provide overlapping coverage so a client can transition to a more suitable AP as it moves. Controller-based WLAN architectures can coordinate aspects of this process. Roaming performance depends on factors such as signal strength, client behavior, authentication design, AP configuration, and network coverage. Proper WLAN planning is therefore important for smooth mobility.

Question 154

Which PPPoE phase discovers an access concentrator?

1. Session phase
2. Discovery phase
3. Authentication phase
4. Network phase

Correct Answer: 2

Explanation:

The PPPoE discovery phase is used to locate an available access concentrator and establish the information needed to create a PPPoE session. After discovery completes, the PPP session can proceed with authentication and network-layer negotiation. Separating discovery from the later session phase helps administrators identify where a broadband connection problem occurs. If discovery messages cannot reach the appropriate access concentrator, the PPP session cannot progress to its normal negotiation stages.

Question 155

Which MPLS field identifies a forwarding equivalence class?

1. EXP
2. TTL
3. Label
4. Bottom-of-stack bit

Correct Answer: 3

Explanation:

The MPLS label identifies the forwarding treatment associated with a packet’s forwarding equivalence class. MPLS routers can use this label to make forwarding decisions within the label-switched network. Other MPLS header fields serve different purposes, such as traffic-class information, lifetime handling, or identifying the bottom of a label stack. Label-based forwarding allows provider networks to handle traffic according to established forwarding paths rather than performing the same full IP lookup at every MPLS hop.

Question 156

Which SNMP database defines managed object information?

1. MIB
2. ACL
3. ARP
4. FIB

Correct Answer: 1

Explanation:

The Management Information Base, or MIB, defines the managed objects that can be monitored or controlled through SNMP. These objects are organized into a structured hierarchy and identified using object identifiers. SNMP managers use this information to understand what values can be requested from network devices. The MIB is therefore an important part of network management because it provides the structure and meaning behind monitored device information. It is distinct from forwarding and address-resolution databases.

Question 157

Which DHCPv6 mode assigns addresses from a server pool?

1. SLAAC
2. Stateful DHCPv6
3. NDP
4. Static IPv6

Correct Answer: 2

Explanation:

Stateful DHCPv6 allows a DHCPv6 server to maintain and assign IPv6 addresses to clients from configured address pools. This resembles the centralized address-assignment model commonly associated with DHCP in IPv4 networks. SLAAC can allow hosts to generate addresses using router advertisements without requiring a DHCPv6 server to allocate the address itself. DHCPv6 can also provide additional configuration information. Administrators select the appropriate method based on the required level of centralized address management.

Question 158

Which Python collection maintains insertion order and allows duplicates?

1. Set
2. Dictionary keys
3. List
4. Frozen set

Correct Answer: 3

Explanation:

A Python list is an ordered collection that can contain duplicate values. Elements remain accessible by their positions, and the collection can be modified after creation. Sets are designed around unique elements, while dictionary keys must be unique within a dictionary. A list is therefore useful when network automation scripts need to preserve a sequence of devices, interfaces, addresses, or configuration tasks while allowing repeated values when necessary.

Question 159

Which SDN protocol is commonly associated with switch flow control?

1. OpenFlow
2. FTP
3. SNMP
4. DNS

Correct Answer: 1

Explanation:

OpenFlow is associated with communication between an SDN controller and compatible forwarding devices for controlling flow entries. It helped establish the concept of separating centralized network control from forwarding behavior. An SDN controller can use a southbound mechanism such as OpenFlow to influence how supported switches handle traffic. SNMP focuses primarily on management and monitoring, while FTP and DNS serve application-layer functions. Understanding OpenFlow helps explain early and foundational SDN architectures.

Question 160

Which NFV concept moves network functions into software?

1. VLAN segmentation
2. Virtual network function
3. MAC learning
4. Route summarization

Correct Answer: 2

Explanation:

A Virtual Network Function, or VNF, implements a network function as software running on suitable virtualized infrastructure instead of requiring a dedicated hardware appliance for every function. Examples can include virtualized routing, firewalling, or load-balancing functions. NFV aims to make network services more flexible and easier to deploy or scale through software-based infrastructure. This differs from VLAN segmentation, MAC learning, and route summarization, which are networking mechanisms rather than virtualization concepts.