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Question 2081Question →

A network security architect is reviewing enterprise core IP addressing service configurations to harden multi-VLAN operations and directory service integration. Match each specific service capability or deployment requirement on the left with its corresponding network protocol, DNS record type, or service mechanism on the right.

Click a left item, then click its matching right item

Items

Injecting access switch attachment details (Circuit ID and Remote ID) into client lease requests before forwarding them across layer 3 boundaries to a centralized server.
Advertising server locations by specifying targeted hostnames, protocol ports, priority, and weight metrics for directory service discovery.
Securing name resolution responses against spoofing and cache poisoning by validating public-key cryptographic signatures attached to resource record sets.
Distributing UTC synchronization metrics from hierarchical reference clocks across network devices to guarantee consistent event logging order.

Matches

Show answer & explanation

Answer

1. Injecting switch attachment details pairs with DHCP Option 82. 2. Advertising server hostnames, ports, priority, and weight pairs with DNS SRV Record. 3. Securing name resolution using cryptographic signatures pairs with DNSSEC. 4. Distributing UTC clock synchronization metrics pairs with NTP.
The pairings are correct because each IP service mechanism directly addresses the stated technical requirement: DHCP Option 82 appends switch attachment metadata to relay requests; DNS SRV records specify target hostnames along with port numbers, priority, and weight; DNSSEC adds cryptographic signature verification to DNS records; and NTP distributes synchronized stratum-based clock references for precise logging across network nodes.

Step-by-Step Solution

1
Analyze the requirement for attaching switch port metadata into DHCP requests across subnets.
Identify that DHCP Relay Agent Information Option (Option 82) allows intermediate Layer 3 relay switches to append subscriber circuit IDs and remote IDs before relaying queries.
Option 82 provides security and targeted IP assignment based on physical switch port locations.
2
Examine service locator requirements that include port, priority, weight, and target hostname information.
Match with the DNS SRV (Service) record specification.
SRV records explicitly publish transport port numbers along with priority and load-balancing weights for service endpoint discovery.
3
Evaluate the cryptographic authentication mechanism for protecting DNS records against tampering and cache poisoning.
Match with DNSSEC (DNS Security Extensions).
DNSSEC adds digital signatures to DNS records to provide origin authority and data integrity verification.
4
Determine the service responsible for propagating accurate hierarchical UTC time synchronization across enterprise logs.
Match with Network Time Protocol (NTP).
NTP uses hierarchical stratum reference clocks to align time values across distributed systems.

Key Concept

Core Enterprise IP Addressing Services and Features
Question 2082Question →

A network engineer is auditing protocol specifications at the transport layer. Match each transport layer feature or mechanism on the left with its corresponding operational protocol characteristic on the right.

Click a left item, then click its matching right item

Items

TCP Three-Way Handshake
UDP Fixed 8-Byte Header
TCP Sliding Window Mechanism
UDP Best-Effort Delivery

Matches

Show answer & explanation

Answer

TCP Three-Way Handshake matches establishing formal session state and sequence numbers; UDP Fixed 8-Byte Header matches minimizing overhead by omitting sequence/acknowledgment fields; TCP Sliding Window Mechanism matches dynamically regulating transmission volume via receiver buffer capacity; UDP Best-Effort Delivery matches transmitting independent datagrams without tracking order or retransmissions.
Each feature aligns directly with its underlying transport protocol design: TCP mechanisms (Three-Way Handshake and Sliding Window) fulfill connection initialization and buffer flow control, whereas UDP attributes (Fixed 8-Byte Header and Best-Effort Delivery) exemplify lightweight, stateless datagram transport.

Step-by-Step Solution

1
Categorize each item on the left as either a connection-oriented (TCP) or connectionless (UDP) mechanism.
TCP items represent stateful connection management and flow control functions. UDP items represent stateless, minimal-overhead datagram transport.
Connection-oriented protocols focus on session state and reliability, whereas connectionless protocols prioritize low latency and minimal overhead.
2
Map TCP mechanisms to session creation and data flow management characteristics.
The Three-Way Handshake corresponds to session state establishment, while the Sliding Window mechanism corresponds to receiver-driven flow control.
TCP requires explicit session initialization and dynamic rate adjustment to prevent receiver buffer exhaustion.
3
Map UDP mechanisms to structural header design and datagram delivery characteristics.
The 8-byte header reflects the absence of connection control fields, and best-effort delivery describes unacknowledged, independent packet transmission.
Connectionless transport eliminates connection setup and tracking fields to reduce header size and processing delay.

Key Concept

Connection-Oriented vs. Connectionless Protocol Characteristics (TCP vs. UDP)
Question 2083Question →

A network technician is auditing Layer 2 frame processing on a managed switch. Port 1 is an access port assigned to VLAN 30 (Engineering), Port 2 is an access port assigned to VLAN 40 (Finance), and Port 24 is configured as an 802.1Q trunk port allowing VLANs 10, 30, and 40, with Native VLAN configured as 10. A workstation connected to Port 1 sends an Ethernet broadcast frame (destination MAC `FF:FF:FF:FF:FF:FF`). Which TWO of the following statements correctly describe how the switch handles this incoming frame? (Select TWO.)

Select all that apply

Show answer & explanation

Answer: The switch floods the broadcast frame out all active access ports assigned to VLAN 30, but does not transmit it out Port 2.; The switch inserts an 802.1Q tag specifying VLAN ID 30 into the Ethernet frame header before forwarding it out Port 24.

Answer

The switch floods the broadcast frame out all active access ports assigned to VLAN 30 while excluding VLAN 40 ports, and encapsulates the frame with an 802.1Q tag specifying VLAN ID 30 when forwarding it over the trunk link.
VLANs operate as separate Layer 2 broadcast domains. Therefore, an Ethernet broadcast originating on a VLAN 30 access port is flooded only to other ports within VLAN 30 (excluding ports in VLAN 40). Additionally, when forwarding this frame out an 802.1Q trunk link where the native VLAN is set to 10, the switch must insert an 802.1Q VLAN tag (VID 30) into the frame to preserve its VLAN membership across the trunk.

Step-by-Step Solution

1
Determine the Layer 2 broadcast domain boundary for the ingress frame.
The ingress frame arrives on Port 1, which is explicitly assigned to VLAN 30. A VLAN isolates broadcast traffic into a single logical broadcast domain.
Broadcast frames are replicated strictly within the originating VLAN boundary, meaning ports assigned to VLAN 40 (such as Port 2) will not receive the frame.
2
Evaluate frame forwarding logic across the 802.1Q trunk port.
Port 24 is configured as an 802.1Q trunk allowing VLAN 30. Because VLAN 30 is non-native (Native VLAN is 10), an 802.1Q header with VLAN ID 30 is inserted.
802.1Q trunking rules dictate that all non-native VLAN traffic MUST be tagged with a 4-byte 802.1Q header upon egress to maintain VLAN identity across switches.

Key Concept

VLAN Broadcast Containment and 802.1Q Trunk Egress Tagging Logic
Question 2084Question →

An edge router receives route advertisements from multiple sources for destination networks overlapping with the target IP address 172.16.10.45172.16.10.45. The router's routing table currently contains the following active operational entries:

Protocol SourceDestination PrefixAdministrative DistanceMetricNext-Hop Interface
EIGRP (Internal)172.16.0.0/16172.16.0.0/1690156160GigabitEthernet0/0
OSPF172.16.10.0/24172.16.10.0/2411020GigabitEthernet0/1
eBGP172.16.10.32/27172.16.10.32/2720100GigabitEthernet0/2
Static Route172.16.10.0/24172.16.10.0/241200GigabitEthernet0/3

When the router processes an inbound IP packet addressed to 172.16.10.45172.16.10.45, which next-hop interface will be selected to forward the packet?

Show answer & explanation

Answer: GigabitEthernet0/2, because longest prefix matching takes precedence over administrative distance during forwarding decisions.

Answer

The router forwards the packet out interface GigabitEthernet0/2 because the eBGP route 172.16.10.32/27 has the longest matching prefix (/27) for the target IP address 172.16.10.45.
When a router receives a packet, it searches its routing table for all entries that match the destination IP address. If multiple matching routes exist with different prefix lengths, the router strictly enforces the Longest Prefix Match (LPM) rule. In this scenario, the target IP 172.16.10.45172.16.10.45 matches 172.16.0.0/16172.16.0.0/16, 172.16.10.0/24172.16.10.0/24, and 172.16.10.32/27172.16.10.32/27. The /27/27 subnet mask is the most specific match (27 bits), making GigabitEthernet0/2 the correct forwarding interface regardless of administrative distance or protocol metric.

Step-by-Step Solution

1
Determine which advertised subnets contain the target IP address 172.16.10.45.
The target address 172.16.10.45 is contained within 172.16.0.0/16, 172.16.10.0/24, and 172.16.10.32/27 (range: 172.16.10.32 - 172.16.10.63).
All three prefix ranges match the target IP destination.
2
Understand the distinction between routing table installation and packet forwarding logic.
Administrative distance (AD) determines which route gets installed in the routing table when identical prefixes exist. Longest Prefix Match (LPM) determines packet forwarding among installed routes.
Multiple routes with different prefix lengths can coexist simultaneously in the routing table.
3
Compare the prefix lengths of all matching installed routes.
Comparing bit mask lengths: /27 (27 bits) > /24 (24 bits) > /16 (16 bits).
Longest Prefix Match requires selecting the route with the highest number of matching network prefix bits.
4
Map the longest matching prefix to its corresponding egress interface.
The /27 prefix route corresponds to interface GigabitEthernet0/2.
GigabitEthernet0/2 is the next-hop interface for 172.16.10.32/27.

Key Concept

Longest Prefix Match (LPM) in Layer 3 Packet Forwarding
Question 2085Question →

Security audit logs indicate that endpoints located in a newly provisioned research laboratory segment (subnet 10.45.80.0/2410.45.80.0/24) are failing to receive dynamic IP address assignments. The organization maintains a centralized redundant DHCP server cluster at 10.45.10.5010.45.10.50. While unicast routing between the subnets is verified to be functioning properly, client broadcast DHCPDISCOVER messages originating from the laboratory segment are stopped at the local router interface. Which configuration change on the gateway router will allow the research segment endpoints to obtain dynamic IP leases from the central cluster?

Show answer & explanation

Answer: Adding the IP helper address pointing to 10.45.10.50 on the router interface serving subnet 10.45.80.0/24

Answer

Configure the IP helper address pointing to 10.45.10.50 on the incoming router interface for subnet 10.45.80.0/24.
Routers do not forward Layer 2 or Layer 3 broadcast messages across subnet boundaries by default. When endpoints emit DHCPDISCOVER broadcasts on subnet 10.45.80.0/24, the router interface serving as their default gateway drops the broadcast. Configuring an IP helper address on that specific incoming interface enables the router to act as a DHCP Relay Agent, converting the broadcast into a unicast frame addressed directly to the central DHCP server at 10.45.10.50.

Step-by-Step Solution

1
Identify the cause of DHCP request drops across subnets
Routers block broadcast frames (such as DHCPDISCOVER sent to 255.255.255.255) by default to prevent broadcast storms across network boundaries.
Layer 3 boundaries isolate broadcast domains.
2
Determine the required relay agent placement
The router interface receiving the client broadcast (subnet 10.45.80.0/24 default gateway) must act as a DHCP Relay Agent.
The relay agent intercept broadcast traffic on the client subnet and encapsulates it into unicast traffic directed to the central server IP address.
3
Select the correct interface configuration command
Applying the IP helper address command on the client-facing interface routes UDP broadcasts (including DHCP on port 67) to 10.45.10.50.
This enables cross-subnet IP addressing service delivery without placing a DHCP server on every local segment.

Key Concept

DHCP Relay / IP Helper Agent Configuration
Estimated Time:1m 15s
Question 2086Question →

A network administrator is troubleshooting a connection failure where internal application servers reject connections from newly deployed management systems. Log analysis reveals that the application servers perform a mandatory reverse IP lookup to validate host identity before establishing a session. While forward lookup zones resolve hostnames to IP addresses correctly, reverse lookups fail for statically addressed hosts because Dynamic DNS (DDNS) updates are only executed by dynamic DHCP clients. Which DNS record type must be manually created in the reverse lookup zone to resolve this issue?

Show answer & explanation

Answer: PTR records mapping the IP addresses of the static management systems to their canonical hostnames

Answer

Manually creating Pointer (PTR) records in the reverse lookup zone resolves IP addresses to domain names for static hosts.
Reverse DNS lookups query the reverse lookup zone (in-addr.arpa for IPv4) to convert an IP address into a domain name. Because statically configured hosts do not automatically register reverse records via DHCP/DDNS integration, PTR (Pointer) records must be manually created to populate the reverse lookup zone and satisfy security authentication checks.

Step-by-Step Solution

1
Analyze the authentication requirement
The application servers require valid reverse DNS resolution (IP address to hostname mapping) to authorize connecting clients.
Security checks often rely on reverse lookup verification to prevent IP spoofing.
2
Identify the cause of missing records
Statically configured hosts do not participate in automated Dynamic DNS (DDNS) registrations handled by DHCP daemons.
Without DDNS or manual intervention, reverse lookup zone entries remain incomplete for static IP addresses.
3
Select the appropriate DNS record type
Create PTR records in the corresponding in-addr.arpa reverse lookup zone.
PTR records specifically map IP addresses to domain names, resolving reverse lookup queries.

Key Concept

DNS Record Types and Reverse Lookup Operation
Question 2087Question →

A network host connected to Switch Port 1 (configured as a Layer 2 access port in VLAN 10) transmits a unicast Ethernet frame destined for a host on Switch Port 2 (also an access port in VLAN 10). The switch's MAC address table already contains an active, valid entry mapping the destination MAC address to Switch Port 2. Which of the following operations will the switch perform upon receiving the frame?

Show answer & explanation

Answer: Inspect the destination MAC address, identify the matching entry for Switch Port 2, and forward the untagged frame exclusively out Switch Port 2.

Answer

The switch inspects the destination MAC address, identifies the matching MAC address table entry for Switch Port 2, and forwards the untagged frame exclusively out Switch Port 2.
When a switch receives a unicast frame on an access port, it looks up the destination MAC address in its MAC address table. Since the address is present (known unicast) and belongs to the same VLAN, the switch forwards the frame directly out the associated port (Switch Port 2) without adding 802.1Q tags.

Step-by-Step Solution

1
Analyze the incoming frame and port mode configuration
The frame arrives on Switch Port 1, which is assigned as an access port in VLAN 10.
Access ports accept untagged frames and associate them internally with their configured VLAN.
2
Perform a MAC address table lookup for the destination address
A matching entry is found linking the destination MAC address directly to Switch Port 2.
Known unicast entries allow the switch to perform microsegmentation and forward traffic directly to the target port.
3
Determine the egress frame handling for an access port
The frame is egressed out Switch Port 2 in standard untagged Ethernet frame format.
802.1Q tags are stripped or never added on access ports connected to end hosts.

Key Concept

Switching Concepts and VLAN Forwarding Logic
Estimated Time:1m 15s
Question 2088Question →

Match each Network Address Translation (NAT) term or implementation type on the left to its corresponding functional description on the right.

Click a left item, then click its matching right item

Items

Inside Local Address
Inside Global Address
Port Address Translation (PAT)
Static NAT

Matches

Show answer & explanation

Answer

Inside Local Address matches the private IP configured on an internal host. Inside Global Address matches the public IP representing the host externally. Port Address Translation (PAT) matches mapping multiple internal IPs to one public IP using source ports. Static NAT matches a permanent one-to-one mapping between an internal private IP and a public IP.
Inside Local Address refers to the private IP assigned to a local network node. Inside Global Address refers to the public IP representing an internal host on public networks. Port Address Translation (PAT) multiplexes multiple private IP addresses onto a single public IP address using distinct Layer 4 source port numbers. Static NAT establishes a fixed one-to-one translation between a specific private IP address and a public IP address.

Step-by-Step Solution

1
Define the internal and external address perspectives defined in Network Address Translation terminology.
Inside Local is the actual private address on the endpoint, whereas Inside Global is the translated public address visible on external networks.
Understanding address naming conventions is essential for configuring and analyzing translation tables.
2
Differentiate between one-to-one translation (Static NAT) and many-to-one translation (PAT).
Static NAT maps one private IP to one public IP permanently, while PAT overloads a single public IP by tracking TCP/UDP port numbers for multiple internal hosts simultaneously.
Different operational requirements dictate whether port multiplexing or static address assignment is appropriate.

Key Concept

NAT and PAT Implementation and Address Classification
Estimated Time:1m 30s
Question 2089Question →

A network architect is implementing specialized DNS configurations across an enterprise hybrid cloud environment. Match each operational requirement on the left with its corresponding DNS resource record type on the right.

Click a left item, then click its matching right item

Items

Specifying transport protocol, service port number, priority, and weight for dynamic service location
Publishing public key cryptographic signatures and policy details to validate email sender domain authenticity
Mapping an IP address back to a canonical fully qualified domain name for reverse resolution auditing
Establishing domain zone authority, primary master server, administrator email, and zone transfer timers

Matches

Show answer & explanation

Answer

Dynamic service discovery with port/protocol parameters maps to SRV Record; email security and cryptographic key publishing maps to TXT Record; IP address to FQDN reverse lookups map to PTR Record; zone authority and synchronization timing metadata map to SOA Record.
Each requirement aligns with the specific functional specification of the corresponding DNS record type: SRV enables port/protocol service discovery, TXT provides text key storage for DKIM/SPF, PTR provides IP-to-FQDN reverse resolution, and SOA governs zone authority and replication timers.

Step-by-Step Solution

1
Analyze service location requirements
Dynamic location of network services requiring specific port numbers, transport protocols, priorities, and weights strictly mandates an SRV record.
Standard host records (A/AAAA/CNAME) do not store protocol or port configuration details.
2
Analyze email security authentication specifications
Storing public keys (DKIM) and SPF policy statements requires a TXT record.
TXT records provide text payload storage designed for security authentication policies without requiring dedicated custom record types.
3
Analyze reverse IP lookup requirements
Mapping an IP address back to its associated FQDN requires a PTR record.
PTR records populate the reverse lookup zone structure (in-addr.arpa / ip6.arpa) specifically used for security validation and logging.
4
Analyze zone administrative parameter requirements
Defining primary name server authority, contact email, serial number, and secondary server refresh timers mandates an SOA record.
Every valid DNS zone must contain exactly one SOA record at the apex to govern zone replication and administrative parameters.

Key Concept

DNS Infrastructure and Resource Record Functionality
Estimated Time:2m 0s
Question 2090Question →

Match each network classification to its primary geographic scope or architectural function.

Click a left item, then click its matching right item

Items

Personal Area Network (PAN)
Storage Area Network (SAN)
Campus Area Network (CAN)
Metropolitan Area Network (MAN)

Matches

Show answer & explanation

Answer

Personal Area Network (PAN) pairs with short-range personal device connection; Storage Area Network (SAN) pairs with dedicated block-level storage access; Campus Area Network (CAN) pairs with interconnecting LANs across adjacent campus buildings; Metropolitan Area Network (MAN) pairs with citywide geographic coverage.
Each network classification aligns directly with its defined spatial scale or storage function: PAN covers immediate short-range personal devices, SAN delivers high-speed block storage access, CAN links multiple building LANs within a campus setting, and MAN encompasses a municipality or city.

Step-by-Step Solution

1
Analyze the geographic reach and structural characteristics of each network type listed.
Short-range peripheral connections correspond to PAN, block-level storage consolidation corresponds to SAN, multi-building LAN aggregation corresponds to CAN, and citywide coverage corresponds to MAN.
Network types are categorized either by spatial distance limits or by specialized infrastructure roles.
2
Pair each network classification to its matching functional description.
PAN matches short-range device connectivity; SAN matches high-speed block storage fabric; CAN matches multi-building LAN interconnectivity; MAN matches citywide or municipal scope.
Connecting each classification to its definition validates understanding of standard networking scope specifications.

Key Concept

Classification of network types based on geographic scale and operational function
Estimated Time:1m 30s
Question 2091Question →

A network administrator is performing packet flow analysis on a network where a host on Subnet A sends traffic to a server on Subnet B through an intermediate Layer 3 router. Which statement correctly describes the encapsulation and de-encapsulation actions executed by the router as it forwards a data packet toward its destination?

Show answer & explanation

Answer: The router strips the incoming Layer 2 frame header and trailer to inspect the Layer 3 IP packet destination, maintains the original IP packet payload, and encapsulates it inside a new Layer 2 frame with source and destination MAC addresses updated for the next hop.

Answer

The router removes the incoming Layer 2 framing, inspects the Layer 3 IP header to determine the next hop, decrements the Time to Live (TTL), and encapsulates the preserved IP packet into a new Layer 2 frame with updated MAC addresses.
The correct response accurately highlights that Layer 3 routers strip incoming Layer 2 frame encapsulation to read the destination IP address, keep the IP packet intact for end-to-end delivery, and construct a new Layer 2 frame with updated source and destination hardware addresses for the outbound link.

Step-by-Step Solution

1
Receive and process Layer 2 frame
The router interface receives the physical signals, validates the Frame Check Sequence (FCS), and strips the Layer 2 Ethernet header and trailer.
Layer 2 framing is hop-to-hop and only delivers data across the single local broadcast domain.
2
Inspect Layer 3 IP packet
The router reads the destination IP address from the IP header, decrements the Time to Live (TTL) field by 1, and recalculates the IP header checksum.
Logical end-to-end addressing resides at Layer 3 and governs route decision-making across subnet boundaries.
3
Re-encapsulate into new Layer 2 frame
The router queries ARP/neighbor discovery for the next-hop MAC address, encapsulates the IP packet into a new Layer 2 frame using its egress interface MAC as the source and the next-hop MAC as the destination, and sends the frame.
Data must be framed appropriately for the specific link layer protocol of the egress network interface.

Key Concept

Hop-by-Hop Layer 2 Re-framing vs End-to-End Layer 3 Packet Preservation
Estimated Time:2m 0s
Question 2092Question →

A network architect is designing an IPv4 subnetting plan for a new high-availability database cluster. The cluster requires IP assignments for 28 database server nodes, 1 dedicated out-of-band monitoring probe, 1 management appliance, and a redundant default gateway deployment using HSRP (which requires 2 physical interface IP addresses and 1 Virtual IP address). Furthermore, enterprise policy dictates that the provisioned subnet must accommodate at least a 25% growth headroom above the total initial IP requirements. Which CIDR prefix length represents the most efficient (smallest) IPv4 subnet that satisfies all requirements, and how many usable host IP addresses will remain unassigned after the initial deployment?

Show answer & explanation

Answer: /26 prefix length with 29 remaining usable host IP addresses

Answer

The most efficient subnet is a /26 prefix length, which leaves 29 remaining usable host IP addresses.
The total required IP count for the deployment is 33 (28 database nodes + 1 probe + 1 appliance + 3 HSRP gateway addresses). Adding 25% headroom requires supporting at least 42 usable IP addresses. A /26 subnet yields 26−2=622^6 - 2 = 62 usable host IP addresses, which is the smallest subnet that accommodates at least 42 hosts. Subtracting the initial 33 assigned addresses leaves 29 unassigned usable host IPs.

Step-by-Step Solution

1
Calculate the total initial host IP requirement
28 (servers) + 1 (probe) + 1 (appliance) + 2 (HSRP physical interfaces) + 1 (HSRP VIP) = 33 required IP addresses.
Redundant gateway protocols such as HSRP require individual IP addresses for each physical router interface plus a shared Virtual IP.
2
Apply the 25% growth headroom expansion requirement
33 × 1.25 = 41.25, which rounds up to a minimum required capacity of 42 usable host IP addresses.
Network design specifications require provisioned subnets to accommodate growth beyond initial deployment counts.
3
Determine the smallest CIDR prefix length supporting at least 42 usable host IPs
A /27 subnet provides 2(32−27)−2=302^{(32-27)} - 2 = 30 usable host IPs (insufficient). A /26 subnet provides 2(32−26)−2=622^{(32-26)} - 2 = 62 usable host IPs (sufficient).
Subnet host capacity is calculated using the formula 2h−22^h - 2, where hh is the number of host bits remaining.
4
Calculate unassigned remaining usable host IP addresses
62 usable IPs - 33 assigned IPs = 29 remaining usable host IP addresses.
Subtracting the initial deployment count from total usable capacity yields remaining capacity for growth.

Key Concept

IPv4 Subnet Mask Calculation and Usable Host Address Estimation
Estimated Time:3m 0s
Question 2093Question →

A senior network engineer is designing a multi-protocol enterprise network architecture utilizing both Interior Gateway Protocols (IGPs) and Exterior Gateway Protocols (EGPs). Which of the following statements correctly describe dynamic routing protocol characteristics and path evaluation behaviors in this environment? (Select TWO)

Select all that apply

Show answer & explanation

Answer: Internal BGP (iBGP) routes have a default Administrative Distance of 200, causing a router to prefer an internal OSPF route (Administrative Distance of 110) if both protocols advertise the exact same prefix length.; Link-state dynamic routing protocols, such as OSPF, exchange Link-State Advertisements (LSAs) to construct a complete link-state database (LSDB) before running the Dijkstra algorithm to calculate the shortest path tree.

Answer

The statement regarding Internal BGP having an Administrative Distance of 200 compared to OSPF's 110, and the statement regarding link-state protocols building an LSDB via LSAs prior to running the Dijkstra algorithm, are both correct.
The statement concerning Internal BGP (iBGP) is correct because iBGP carries a default Administrative Distance of 200, which is higher (less preferred) than OSPF's default AD of 110 when choosing between equal prefix matches. The statement concerning link-state protocols is also correct because OSPF routers gather topology information via LSAs to populate the local Link-State Database (LSDB) before running the Dijkstra algorithm to calculate optimal routes.

Step-by-Step Solution

1
Evaluate the Administrative Distance relationship between iBGP and OSPF.
OSPF routes have an Administrative Distance (AD) of 110, whereas iBGP routes have an AD of 200. Because lower AD indicates higher trustworthiness, OSPF is preferred over iBGP for equal prefix matches.
Administrative Distance is the first tie-breaker used by the routing table manager when multiple protocols advertise the same prefix.
2
Analyze link-state routing protocol convergence and database synchronization mechanisms.
OSPF routers synchronize their Link-State Database (LSDB) by exchanging Link-State Advertisements (LSAs) and then run Dijkstra's Shortest Path First (SPF) algorithm.
Unlike distance-vector protocols that share routing tables by rumor, link-state protocols require a complete topology map prior to path computation.
3
Verify OSI layer boundaries for routing protocols and BGP transport requirements.
Routing decisions occur at Layer 3 using IP headers, and BGP uses TCP port 179 for reliable peering.
Layer 2 MAC headers change at each router hop, and BGP relies on TCP's connection-oriented guarantees rather than connectionless UDP.

Key Concept

Administrative Distance hierarchy and Link-State Routing Protocol convergence mechanisms
Estimated Time:2m 0s
Question 2094Question →

A network administrator assigns the IPv4 prefix 192.168.10.0/29192.168.10.0/29 to a small network segment. Which of the following statements regarding this subnet are correct? (Select TWO)

Select all that apply

Show answer & explanation

Answer: The subnet mask in dotted-decimal notation is 255.255.255.248.; The network provides a total of 6 usable IP addresses for host devices.

Answer

The subnet mask is 255.255.255.248 and the network provides a total of 6 usable IP addresses for host devices.
For a /29 subnet, there are 3 host bits remaining (32−29=332 - 29 = 3). The subnet mask corresponds to 255.255.255.248. The total number of IP addresses in the block is 23=82^3 = 8. Subtracting the network identifier (192.168.10.0) and the broadcast address (192.168.10.7) leaves 6 usable IP addresses for hosts.

Step-by-Step Solution

1
Calculate the subnet mask from CIDR notation /29.
The subnet mask has 29 network bits and 3 host bits. In dotted-decimal form, 255.255.255.248.
Converting /29 to binary gives 11111111.11111111.11111111.11111000, which equals 255.255.255.248.
2
Calculate total IP addresses and usable host addresses.
Total addresses = 23=82^3 = 8. Usable host addresses = 8−2=68 - 2 = 6.
The network ID (192.168.10.0) and broadcast address (192.168.10.7) cannot be assigned to hosts.

Key Concept

IPv4 Subnetting and Usable Host Calculation
Question 2095Question →

A network technician is configuring a dedicated VLAN for a department that requires 3030 desktop computers and 11 IP phone, requiring a total of 3131 usable host IPv4 addresses. Which subnet mask is the most efficient choice that fulfills this requirement without wasting unnecessary address space?

Show answer & explanation

Answer: 255.255.255.192

Answer

255.255.255.192
To host 3131 devices, the subnet must offer at least 3131 usable host IP addresses. The formula for usable IPs is 2n−22^n - 2, where nn represents host bits. A /27 subnet (255.255.255.224255.255.255.224) provides 25−2=302^5 - 2 = 30 usable IPs, which is one address short. Therefore, the next larger subnet size is required, which is /26 (255.255.255.192255.255.255.192), giving 26−2=622^6 - 2 = 62 usable host IPs.

Step-by-Step Solution

1
Calculate total host IP addresses required including host overhead.
31 usable IP addresses are required.
The subnet must support 30 computers and 1 IP phone (30 + 1 = 31).
2
Apply the usable host capacity formula 2n−2≥H2^n - 2 \ge H, where nn is the number of host bits and HH is the required usable host count.
For n=5n=5, 25−2=302^5 - 2 = 30 usable addresses (insufficient). For n=6n=6, 26−2=622^6 - 2 = 62 usable addresses (sufficient).
Two addresses in every subnet must be reserved for the network ID and the directed broadcast address.
3
Determine the prefix length and dotted-decimal subnet mask corresponding to 66 host bits.
Prefix length is 32−6=/2632 - 6 = /26. The decimal mask is 255.255.255.192255.255.255.192.
A prefix of /26 leaves 6 bits for hosts (255.255.255.110000002=255.255.255.192255.255.255.11000000_2 = 255.255.255.192).

Key Concept

IPv4 Usable Host Count Calculation
Estimated Time:1m 30s
Question 2096Question →

A network operations team deploys a new trunk link between access switch SW-Acc-02 and core switch SW-Core-01. Users connected to ports assigned to VLAN 20 on SW-Acc-02 report that they cannot reach servers on VLAN 20 located behind SW-Core-01, while users on VLAN 10 experience normal connectivity.

The current interface configurations are shown below:

SW-Acc-02 Interface Configuration:
text
interface GigabitEthernet1/0/48
switchport mode trunk
switchport trunk native vlan 99
switchport trunk allowed vlan 10,99

SW-Core-01 Interface Configuration:
text
interface GigabitEthernet0/24
switchport mode trunk
switchport trunk native vlan 99
switchport trunk allowed vlan 10,20,99

Which configuration change on SW-Acc-02 will resolve the loss of connectivity for VLAN 20 traffic across the trunk?

Show answer & explanation

Answer: Add VLAN 20 to the switchport trunk allowed vlan list on interface GigabitEthernet1/0/48.

Answer

Add VLAN 20 to the switchport trunk allowed vlan list on interface GigabitEthernet1/0/48.
The correct answer adds VLAN 20 to the allowed list on SW-Acc-02. An 802.1Q trunk interface only forwards and receives traffic for VLANs specified in its allowed VLAN list. Because SW-Acc-02 was configured to allow only VLANs 10 and 99, all frames for VLAN 20 were dropped at the ingress/egress interface GigabitEthernet1/0/48.

Step-by-Step Solution

1
Analyze the trunk configuration on SW-Acc-02.
Interface GigabitEthernet1/0/48 is configured with 'switchport trunk allowed vlan 10,99', which restricts trunk traffic exclusively to VLAN 10 and VLAN 99.
By default, trunks allow all VLANs unless explicitly filtered using the allowed VLAN list command.
2
Compare SW-Acc-02 allowed VLAN list with SW-Core-01 configuration.
SW-Core-01 allows VLAN 10, 20, and 99, but SW-Acc-02 drops incoming and outgoing VLAN 20 tagged frames at interface GigabitEthernet1/0/48 due to the restrictive allowed list.
802.1Q trunks drop frames tagged with VLAN IDs that are not explicitly included in their allowed VLAN filter.
3
Determine the necessary remediation command.
Executing 'switchport trunk allowed vlan add 20' or modifying the allowed list to '10,20,99' on SW-Acc-02 allows VLAN 20 frames to traverse the trunk link.
Both switches at the ends of an 802.1Q trunk must explicitly permit the VLANs intended to cross the inter-switch link.

Key Concept

802.1Q Trunk Allowed VLAN List Pruning and Filtering
Estimated Time:1m 30s
Question 2097Question →

A network engineer is integrating a new remote branch office subnet (172.16.40.0/24172.16.40.0/24) connected to corporate headquarters through a Layer 3 site-to-site VPN. Client workstations at the branch fail to obtain dynamic IP configurations from the central enterprise DHCP server (10.10.10.510.10.10.5). Packet captures confirm that client DHCPDISCOVER broadcast frames arrive at the branch router's inbound local interface, but no DHCPOFFER packets are returned. Which configuration change on the branch router directly resolves this connectivity failure?

Show answer & explanation

Answer: Configure an IP helper address pointing to 10.10.10.510.10.10.5 on the branch router's LAN interface facing the client subnet.

Answer

Configure an IP helper address pointing to 10.10.10.510.10.10.5 on the branch router's LAN interface facing the client subnet.
Configuring an IP helper address on the client-facing LAN interface allows the branch router to intercept client broadcast DHCPDISCOVER messages (UDP port 67). The router converts these broadcasts into unicast IP packets targeted directly at the remote central DHCP server (10.10.10.510.10.10.5) across the routed VPN, populating the gateway IP field (GIADDR) so the server can assign an address from the 172.16.40.0/24172.16.40.0/24 scope.

Step-by-Step Solution

1
Analyze the traffic type and network boundary condition.
Client workstations issue broadcast DHCPDISCOVER requests (255.255.255.255255.255.255.255) on the local LAN. Routers drop Layer 3 broadcast traffic by default.
Broadcast packets cannot naturally traverse the Layer 3 site-to-site VPN to reach the central server at 10.10.10.510.10.10.5.
2
Determine the correct service mechanism and placement.
A DHCP Relay Agent (IP Helper) must be deployed on the router interface receiving the client broadcasts (the local LAN interface).
The relay agent intercept broadcasts on the ingress LAN interface, encapsulates them into unicast packets directed to 10.10.10.510.10.10.5, and inserts gateway IP address (GIADDR) information so the server knows which scope to allocate from.
3
Evaluate distractor configurations against technical requirements.
Placing the helper on the WAN interface, creating CNAME records, or forwarding UDP port 69 (TFTP) fails to address the root cause of unforwarded DHCP UDP 67/68 broadcasts.
Only configuring the IP helper address on the LAN interface correctly converts local incoming broadcasts to unicast packets sent to the central server.

Key Concept

DHCP Relay Agent and IP Helper Placement
Question 2098Question →

A network administrator configures an IEEE 802.1Q trunk interface on a switch and executes the command `switchport trunk native vlan 20`. How does the switch handle outgoing frames belonging to VLAN 20 on this trunk interface?

Show answer & explanation

Answer: It transmits the frames onto the link without adding an 802.1Q VLAN tag.

Answer

It transmits the frames onto the link without adding an 802.1Q VLAN tag.
On an IEEE 802.1Q trunk port, traffic belonging to the designated native VLAN is transmitted across the link without an added 802.1Q header tag. Because VLAN 20 is configured as the native VLAN, outgoing frames for VLAN 20 are sent untagged.

Step-by-Step Solution

1
Identify the operation of IEEE 802.1Q native VLANs on trunk interfaces.
IEEE 802.1Q defines a native VLAN for trunk links where traffic is forwarded without an 802.1Q header tag.
Native VLAN configuration allows untagged frame transmission across trunk links for backward compatibility with non-tagging devices.
2
Apply the configuration command to VLAN 20.
Frames associated with VLAN 20 on this specific port will be egressed untagged.
The command explicitly sets VLAN 20 as the native VLAN for the trunk port.

Key Concept

802.1Q Native VLAN Tagging Behavior
Question 2099Question →

An infrastructure team is deploying Voice over IP (VoIP) telephony across a corporate network. To ensure IP phones can dynamically discover the target hostname, listening port number, and transport protocol of the primary SIP server via domain queries, which DNS resource record type must be provisioned in the internal DNS zone?

Show answer & explanation

Answer: SRV record

Answer

The SRV record must be provisioned because it includes host, protocol, and port details required for service discovery.
The SRV record (Service Location record) is specifically formatted (e.g., _sip._tcp.example.com) to specify the location of servers for specified services, including the target domain name, port number, priority, and weight.

Step-by-Step Solution

1
Identify the operational requirement for client endpoint discovery.
IP phones require locating a specific service (SIP) along with its associated transport protocol (e.g., UDP/TCP) and port number (e.g., 5060).
Standard host resolution records only map names to IP addresses without service port context.
2
Evaluate standard DNS record capabilities against service discovery requirements.
Only an SRV (Service Location) record contains fields for service name, protocol, priority, weight, port, and target host.
SRV records are explicitly designed to allow clients to locate services operating on non-standard ports or specific server instances.

Key Concept

DNS SRV Record for Service Location
Question 2100Question →

A system engineer is updating perimeter firewall rules to allow local network devices to retrieve operating system installation images from a Trivial File Transfer Protocol (TFTP) provisioning server. Which transport protocol and port combination must be permitted inbound on the server?

Show answer & explanation

Answer: UDP port 69

Answer

UDP port 69
Trivial File Transfer Protocol (TFTP) operates on UDP port 69. It provides low-overhead, connectionless file transfer suitable for devices requesting firmware or PXE network boot images.

Step-by-Step Solution

1
Identify the protocol specified for retrieving boot images.
The scenario identifies Trivial File Transfer Protocol (TFTP).
TFTP is specifically designed for simple, unauthenticated file downloads during network bootstrapping.
2
Determine the transport protocol and standard service port for TFTP.
TFTP listens on UDP port 69.
Because TFTP relies on UDP rather than TCP, inbound requests must be permitted on UDP destination port 69.

Key Concept

Trivial File Transfer Protocol (TFTP) port and transport protocol assignment
Estimated Time:1m 0s
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