Networking Concepts

538 questions

All types538 Multiple choice279 Multiple select117 Numeric19 Matching95 Ordering28

A network administrator is configuring dynamic IP addressing and name resolution services across an enterprise network. The organization requires client hostnames to be automatically registered in the internal DNS zone whenever a host receives an IPv4 address lease from the centralized DHCP server. Which TWO of the following steps must be configured to enable dynamic DNS (DDNS) updates between the DHCP and DNS servers?

Select all that apply

Configure the DHCP server with authentication credentials to send dynamic update requests to the authoritative DNS server on behalf of clients

Configure the primary DNS zone properties to permit secure dynamic updates from the authorized DHCP server

Configure an IP helper address on the authoritative DNS server pointing to the DHCP server to relay PTR record updates

Create static CNAME resource records for all host IP addresses in the DHCP pool prior to lease allocation

Reconfigure the DNS update transport settings to transmit dynamic zone records over UDP port 67

Show answer & explanation

Answer: Configure the DHCP server with authentication credentials to send dynamic update requests to the authoritative DNS server on behalf of clients; Configure the primary DNS zone properties to permit secure dynamic updates from the authorized DHCP server

Answer

To establish dynamic DNS (DDNS) integration, the administrator must permit secure dynamic updates on the primary DNS zone and configure the DHCP server with credentials authorized to send update requests to the authoritative DNS server on behalf of DHCP clients.

Dynamic DNS (DDNS) allows automatic updating of DNS database records when IP address leases are granted. For this to operate seamlessly, the primary DNS zone must be set to allow secure dynamic updates, and the DHCP server must be configured with authorized credentials to submit host (A) and pointer (PTR) record creation requests to the DNS server.

Step-by-Step Solution

Analyze how dynamic host resolution updates interact during DHCP lease allocation.

Identify that the DHCP server creates or updates Forward (A) and Reverse (PTR) DNS records when handing out leases.

Centralized DDNS offloads domain registration responsibilities from individual client endpoints to the DHCP infrastructure.

Determine the necessary permission settings on the DNS server.

Enable secure dynamic updates on the authoritative zone of the primary DNS server.

Authoritative DNS servers reject unauthenticated or unpermitted dynamic record update attempts by default.

Determine the necessary credentials on the DHCP server.

Supply the DHCP server with authentication credentials (e.g., TSIG key or account) authorized to modify DNS zone records.

The DNS server requires valid security context from the DHCP server to permit record creation and modifications.

Key Concept

Dynamic DNS (DDNS) Integration with DHCP Services

Estimated Time:1m 30s

Question 2Question →

A network engineer is analyzing traffic traversing an enterprise Layer 3 switch configured for inter-VLAN routing. A client host on VLAN 10 sends a request to a destination server on VLAN 20. When the switch receives the frame on its VLAN 10 interface and routes it out through the VLAN 20 interface, which of the following best describes the de-encapsulation and re-encapsulation process performed by the switch?

The switch de-encapsulates the frame up to Layer 3, replaces the source IP address in the packet header with its own interface IP address, and prepends a new Layer 2 Ethernet header.

The switch strips the incoming Layer 2 Ethernet header and trailer, inspects the Layer 3 destination IP address to determine the egress interface, and encapsulates the IP packet into a new Layer 2 Ethernet frame with updated source and destination MAC addresses.

The switch decapsulates the transmission up to Layer 4, modifies the TCP destination port field to indicate the egress VLAN ID, and forwards the original Layer 2 frame out the target port without altering MAC addresses.

The switch encapsulates the incoming Layer 2 frame inside an outer UDP header to tunnel the frame across VLAN boundaries without modifying the existing Ethernet header.

Show answer & explanation

Answer: The switch strips the incoming Layer 2 Ethernet header and trailer, inspects the Layer 3 destination IP address to determine the egress interface, and encapsulates the IP packet into a new Layer 2 Ethernet frame with updated source and destination MAC addresses.

Answer

When a Layer 3 device (such as a router or Layer 3 switch) routes traffic between subnets/VLANs, it de-encapsulates the incoming Layer 2 Ethernet frame to extract the enclosed Layer 3 IP packet. It inspects the destination IP address to determine the appropriate egress interface. Before transmitting onto the destination VLAN, the device re-encapsulates the IP packet into a brand new Layer 2 Ethernet frame. The new frame uses the router's egress interface MAC as the source MAC address and the destination host's MAC (or next hop MAC) as the destination MAC address. The original IP packet payload and end-to-end IP addresses remain unchanged (except for TTL decrementing and checksum updating).

Step-by-Step Solution

Analyze the incoming frame at Layer 2

The Layer 3 switch receives the Ethernet frame on VLAN 10, verifies the frame check sequence (FCS) trailer, and verifies that the destination MAC matches its own gateway MAC address.

Layer 2 processing requires verifying frame integrity and confirming the frame is addressed to the default gateway.

De-encapsulate the packet at Layer 3

The switch strips the Layer 2 Ethernet header and trailer to expose the enclosed IP packet.

To route traffic between different subnets/VLANs, the network layer header must be inspected.

Perform routing lookup and update IP header fields

The switch reads the destination IP address, checks its routing table, decrements the Time to Live (TTL) value by 1, and recalculates the IP header checksum.

The Layer 3 header provides forwarding instructions across network boundaries.

Re-encapsulate the packet into a new Layer 2 frame

The switch appends a new Layer 2 Ethernet header containing its egress interface MAC address as the source MAC, the destination server's MAC address as the destination MAC, and recalculates the FCS trailer for VLAN 20.

Each physical or logical link (VLAN) requires local Layer 2 addressing for delivery to the destination or next-hop device.

Key Concept

Hop-by-hop encapsulation and de-encapsulation during Layer 3 routing

Estimated Time:1m 30s

Question 3Question →

A network architect is evaluating an existing industrial facility deployment that uses a hybrid physical star, logical bus network topology. Which of the following statements accurately describe the structural and operational characteristics of this hybrid network layout? (Select TWO.)

Select all that apply

A disruption or cable break between an individual workstation and its local switch node impacts only that specific host.

A failure along the central bus backbone segment disrupts inter-group communications across all attached star clusters.

Traffic sent between distinct virtual local area networks (VLANs) across the bus automatically bypasses the need for Layer 3 inter-VLAN routing.

Framing units sent across the logical bus architecture are formatted as Layer 3 packets directly processed by end-station network interfaces.

Show answer & explanation

Answer: A disruption or cable break between an individual workstation and its local switch node impacts only that specific host.; A failure along the central bus backbone segment disrupts inter-group communications across all attached star clusters.

Answer

The correct characteristics are that a single cable break between a workstation and its local hub/switch impacts only that workstation, and a failure on the main bus backbone severs communication between connected star clusters.

A hybrid physical star, logical bus topology uses star wired drops to local switch/hub clusters connected via a shared bus backbone. The physical star element ensures that a drop cable failure only disconnects the affected endpoint. Conversely, because the shared bus serves as the common interconnect for all clusters, a break in the central bus segment disables inter-segment transmission across the entire network.

Step-by-Step Solution

Analyze physical star topology properties.

Individual endpoint runs to central distribution devices isolate localized cable failures.

Physical star wiring isolates link-level faults to individual ports.

Analyze logical bus backbone properties.

The backbone serves as a shared transmission medium linking nodes together.

If the main bus backbone severs or fails, communications spanning multiple star segments cannot traverse the central bus.

Evaluate distractor concepts regarding OSI layers and VLAN boundaries.

VLAN boundaries always require Layer 3 routing, and topology bus access uses Layer 2 data frames.

Topologies function at the Data Link layer and do not eliminate Layer 3 boundary requirements.

Key Concept

Physical vs. Logical Network Topologies (Star-Bus Hybrid)

Question 4Question →

During a routine internal security audit, a network analyst discovers that administrators are using Telnet to remotely configure network infrastructure devices, exposing authentication credentials in unencrypted cleartext across internal subnets. Security policy requires immediately replacing this practice with Secure Shell (SSH) to secure all interactive administrative sessions. Which default port and transport layer protocol combination must be permitted on internal firewalls to allow SSH traffic?

TCP port 22

UDP port 22

TCP port 23

UDP port 23

Show answer & explanation

Answer: TCP port 22

Answer

TCP port 22

Secure Shell (SSH) operates over TCP port 22 by default. SSH provides encrypted terminal management sessions and relies on TCP's connection-oriented delivery to maintain session integrity.

Step-by-Step Solution

Identify the target secure administration protocol.

The scenario requires implementing Secure Shell (SSH) to replace unencrypted Telnet sessions.

SSH encrypts management traffic, preserving confidentiality for administrative credentials and commands.

Determine the transport layer protocol required by SSH.

SSH requires Transmission Control Protocol (TCP) to ensure reliable, connection-oriented data delivery.

Interactive shell sessions depend on ordered delivery and error recovery provided by TCP.

Identify the standard IANA assigned port for SSH.

SSH operates on default port 22.

Standard network firewall rules reference IANA default port allocations for service filtering.

Key Concept

Common Ports and Protocols - SSH (TCP 22) vs Telnet (TCP 23)

Question 5Question →

An IT infrastructure team is upgrading a data center's storage and core network architecture by introducing a dedicated Storage Area Network (SAN) alongside a full-mesh topology for core switches. Which of the following statements correctly describe the technical characteristics and operational trade-offs of these implementations? (Select TWO.)

Select all that apply

A full-mesh topology delivers complete link redundancy and high fault tolerance by connecting every node to every other node, requiring

\frac{n(n-1)}{2}

total physical links for

n

nodes.

A SAN provides a dedicated, high-speed network environment optimized specifically for block-level storage access by servers.

Isolating core switch ports into different VLANs allows hosts on separate VLANs to communicate across the physical mesh without a Layer 3 routing device.

A SAN operates primarily by providing file-level file system sharing using high-level Layer 7 protocols like HTTP and FTP.

Show answer & explanation

Answer: A full-mesh topology delivers complete link redundancy and high fault tolerance by connecting every node to every other node, requiring $\frac{n(n-1)}{2}$ total physical links for $n$ nodes.; A SAN provides a dedicated, high-speed network environment optimized specifically for block-level storage access by servers.

Answer

A full-mesh topology provides complete redundancy using

\frac{n(n-1)}{2}

physical links, and a Storage Area Network (SAN) provides dedicated block-level access to consolidated storage devices.

The statement regarding full-mesh topology accurately identifies its fault-tolerant nature and physical link calculation formula

\frac{n(n-1)}{2}

. Additionally, the statement describing a Storage Area Network (SAN) correctly highlights its dedicated role in delivering block-level storage access to enterprise servers.

Step-by-Step Solution

Analyze full-mesh topology characteristics

Full-mesh topologies eliminate single points of failure by interconnecting every node directly to every other node using

\frac{n(n-1)}{2}

physical links.

This mathematical formula calculates the total un-directed links required for complete mesh interconnection.

Evaluate Storage Area Network (SAN) architecture

A SAN is designed for high-throughput, low-latency block-level data access rather than file-level network sharing.

Block-level access enables operating systems to treat remote SAN volumes as locally attached physical drives.

Identify misconceptions in distractors

Inter-VLAN communication strictly requires Layer 3 routing, and file-level sharing describes NAS rather than SAN.

VLAN boundaries enforce Layer 2 isolation, while file sharing operates at higher network protocol layers above raw block access.

Key Concept

Full-Mesh Topology and Storage Area Network (SAN) Architecture

Question 6Question →

A network technician is deploying a new fleet of VoIP desktop phones across multiple subnets. To automate initial provisioning, each phone must automatically receive the IP address or hostname of its TFTP boot server from the central DHCP server upon starting up. Which DHCP option should the technician configure within the DHCP scope to supply this provisioning server information?

Option 66

Option 82

Option 6

Option 42

Show answer & explanation

Answer: Option 66

Answer

Option 66 is used in DHCP scope configurations to specify the TFTP server hostname or IP address required by booting clients like VoIP phones and PXE-enabled computers.

DHCP Option 66 is explicitly designated in core networking standards to provide the TFTP server name or IP address to DHCP clients. This allows unconfigured network devices, such as VoIP phones or PXE boot workstations, to automatically contact their boot server and download operating configurations.

Step-by-Step Solution

Identify the service requirement from the scenario.

The devices need automated TFTP provisioning server information delivered via DHCP.

VoIP phones require a boot server address during IP lease acquisition to download firmware and configuration files.

Map the requirement to standard DHCP option codes.

DHCP Option 66 is defined specifically for TFTP Server Name / IP Address.

Standardized DHCP options allow centralized addressing services to pass vendor-neutral and protocol-specific metadata to client endpoints.

Key Concept

DHCP Options for Automated IP Addressing Services

Estimated Time:1m 0s

Question 7Question →

A network technician needs to assign an IPv4 subnet mask to a network segment that must accommodate $28$ usable host devices. Which CIDR notation prefix fulfills this requirement while reserving the minimal amount of unused IP addresses?

/28

/27

/26

/29

Show answer & explanation

Answer: /27

Answer

The /27 prefix is the smallest subnet mask that provides at least 28 usable host IP addresses.

A /27 prefix allocates 5 bits for host addressing (

32 - 27 = 5

), resulting in

2^5 = 32

total IP addresses. Subtracting

2

for the network and broadcast addresses leaves

30

usable IP addresses (

32 - 2 = 30

). This is the smallest standard subnet mask that accommodates

28

hosts.

Step-by-Step Solution

Calculate the total required IP addresses by adding 2 reserved addresses (network ID and broadcast address) to the needed host count.

28\text{ hosts} + 2\text{ reserved} = 30\text{ total addresses needed}

Every IPv4 subnet requires one network address and one broadcast address, which cannot be assigned to hosts.

Find the smallest block size (power of 2) that is greater than or equal to the total required addresses.

2^5 = 32\text{ total addresses}

, requiring

5

host bits.

Subnet block sizes must be powers of two.

Subtract the host bits from 32 to determine the network prefix length.

32 - 5 = /27

An IPv4 address contains 32 total bits.

Key Concept

IPv4 Host Capacity and Subnet Mask Selection

Estimated Time:45s

Question 8Question →

A network host connected to interface FastEthernet $0/12$ on a Layer 2 switch transmits an Address Resolution Protocol (ARP) request broadcast frame. Interface FastEthernet $0/12$ is configured as an access port belonging to VLAN $50$ . Which of the following actions will the switch perform upon receiving this frame?

The switch forwards the frame out all operational access ports assigned to VLAN

50

, excluding interface FastEthernet

0/12

The switch floods the frame out all operational ports across all configured VLANs on the switch, excluding interface FastEthernet

0/12

The switch strips the Layer 2 Ethernet headers and converts the broadcast frame into a Layer 3 IP packet before forwarding.

The switch inserts an 802.1Q VLAN header tag into the frame before forwarding it out all other access ports assigned to VLAN

50

Show answer & explanation

Answer: The switch forwards the frame out all operational access ports assigned to VLAN $50$ , excluding interface FastEthernet $0/12$ .

Answer

The switch forwards the broadcast frame out all active access ports configured for VLAN 50, excluding the receiving port FastEthernet 0/12.

A Virtual Local Area Network (VLAN) creates a logical Layer 2 broadcast domain. When a broadcast frame (such as an ARP request) is received on an access port, the switch floods that frame to every active port belonging to the same VLAN, while excluding the port on which the frame originally arrived to prevent loops.

Step-by-Step Solution

Identify the frame type and ingress port configuration.

The frame is an ARP request broadcast (destination MAC ff:ff:ff:ff:ff:ff) arriving on access port FastEthernet 0/12 assigned to VLAN 50.

Understanding the PDU type and port membership determines how the switch handles forwarding.

Determine the Layer 2 broadcast domain boundary.

VLAN 50 forms a logical Layer 2 broadcast domain isolated from all other VLANs on the switch.

Broadcast frames are contained strictly within the originating VLAN.

Apply Layer 2 switch flooding behavior rules.

The switch floods the broadcast frame to all active interfaces assigned to VLAN 50, except the ingress port FastEthernet 0/12, without applying 802.1Q tags to access port output.

Standard switch logic dictates flooding broadcast traffic within the VLAN while preventing loopback to the source port.

Key Concept

VLAN Broadcast Domain Boundaries and Layer 2 Flooding Logic

Estimated Time:1m 15s

Question 9Question →

A network administrator is configuring perimeter security rules to allow an internal Remote Authentication Dial-In User Service (RADIUS) server to authenticate wireless users against an external partner system. Which transport protocol and destination port pair must be permitted through the firewall for standard RADIUS authentication traffic?

UDP port 1812

TCP port 1812

UDP port 1813

TCP port 49

Show answer & explanation

Answer: UDP port 1812

Answer

Standard RADIUS authentication traffic operates over UDP port 1812.

UDP port 1812 is the standard IANA-assigned port for RADIUS authentication and authorization traffic. RADIUS uses UDP for lightweight connectionless transmission.

Step-by-Step Solution

Identify the protocol and required function in the scenario

The scenario requires RADIUS performing authentication.

RADIUS separates authentication/authorization (port 1812) from accounting functions (port 1813).

Determine the transport protocol used by RADIUS

RADIUS uses UDP rather than TCP at the Transport Layer.

RADIUS relies on connectionless UDP transport and handles retransmissions at the application layer.

Select the correct port and transport protocol pairing

UDP port 1812 is the official standard IANA port for RADIUS authentication.

UDP 1812 ensures RADIUS authentication requests reach the RADIUS daemon properly.

Key Concept

RADIUS Port Numbers and Protocols

Estimated Time:1m 0s

Question 10Question →

A network engineer is configuring a core router that learns a path to the $10.50.0.0/16$ network through multiple routing sources simultaneously: an internal OSPF advertisement, a RIPv2 advertisement, and a manually configured static route. All sources advertise the exact same prefix length. Which path will the router install into its active routing table, and why?

The static route, because static routes have a lower Administrative Distance than OSPF and RIPv2.

The OSPF route, because dynamic routing protocol updates operate at Layer 2 to bypass IP routing table overhead.

The RIPv2 route, because distance-vector protocols automatically override link-state protocols when hop counts are equal.

All three routes simultaneously in a round-robin load-balancing group across different VLAN broadcast domains.

Show answer & explanation

Answer: The static route, because static routes have a lower Administrative Distance than OSPF and RIPv2.

Answer

The static route is installed into the routing table because it has the lowest Administrative Distance (AD = 1) compared to OSPF (AD = 110) and RIPv2 (AD = 120) for the exact same destination prefix.

When a router receives multiple routes to the exact same destination network prefix from different routing sources, it uses Administrative Distance (AD) to select the best route. Default AD values are: Static route = 1, OSPF = 110, and RIPv2 = 120. Because lower AD indicates higher trustworthiness, the static route is selected.

Step-by-Step Solution

Identify the advertised destination prefix lengths across all sources.

All three routes offer identical prefix lengths (

10.50.0.0/16

), so Longest Prefix Match (LPM) ties.

When prefix lengths match, the router evaluates Administrative Distance (AD) to determine trustworthiness.

Compare the Administrative Distance values of the competing routing sources.

Static Route AD = 1, OSPF AD = 110, RIPv2 AD = 120.

Lower Administrative Distance values indicate higher administrative preference and trustworthiness.

Select the winning route to install in the IP routing table.

The static route with AD = 1 is selected.

The router selects the path with the lowest Administrative Distance.

Key Concept

Administrative Distance Hierarchy and Route Selection

Question 11Question →

Match each dynamic routing protocol or routing concept to its correct characteristic or functional definition.

Click a left item, then click its matching right item

Show answer & explanation

Answer

Open Shortest Path First (OSPF) pairs with Link-state IGP using Dijkstra's algorithm and a cost metric based on reference bandwidth. Border Gateway Protocol (BGP) pairs with Path-vector EGP that makes routing decisions based on autonomous system path and policy attributes. Routing Information Protocol version 2 (RIPv2) pairs with Distance-vector IGP using hop count (maximum 15) as its metric with 30-second periodic updates. Administrative Distance (AD) pairs with Trustworthiness metric ranging from 0 to 255 used by routers to rank route sources.

Each protocol and routing term is accurately aligned with its corresponding algorithm, metric structure, and administrative scope.

Step-by-Step Solution

Analyze OSPF operational attributes.

OSPF operates as a link-state Interior Gateway Protocol (IGP) using cost computed from interface bandwidth via the Dijkstra algorithm.

Link-state protocols build full topology maps before calculating shortest path trees.

Analyze BGP operational attributes.

BGP functions as a path-vector Exterior Gateway Protocol (EGP) routing between Autonomous Systems using AS-Path attributes.

Path-vector protocols prevent loops at an inter-domain scale without needing link-state maps of external systems.

Analyze RIPv2 operational attributes.

RIPv2 is a distance-vector protocol utilizing hop count as its primary metric with a 15-hop boundary.

Distance-vector routing relies on directional vectors and periodic table updates sent to directly connected neighbors.

Analyze Administrative Distance.

Administrative Distance is an integer ranking from 0 (most trusted) to 255 (untrusted) used when multiple protocols advertise an identical destination path.

Routers must select a single route source to install into the IP routing table when prefix lengths are equal.

Key Concept

Dynamic Routing Protocols and Path Selection Principles

Estimated Time:1m 30s

Question 12Question →

A network engineer is configuring access control lists (ACLs) on a perimeter firewall to support infrastructure maintenance and monitoring. The configuration must allow network routers to synchronize system clocks with an internal time server and send asynchronous event notifications to a centralized monitoring station. Which of the following port and transport protocol combinations must be permitted through the firewall? (Select TWO.)

Select all that apply

UDP port 123

UDP port 162

TCP port 123

TCP port 162

Show answer & explanation

Answer: UDP port 123; UDP port 162

Answer

UDP port 123 and UDP port 162 must be permitted.

Network Time Protocol (NTP) relies on UDP port 123 to synchronize device system clocks with low overhead and minimal delay. Simple Network Management Protocol (SNMP) traps use UDP port 162 to asynchronously push alert notifications from network devices to a central management server.

Step-by-Step Solution

Identify the required network service for time synchronization.

Network Time Protocol (NTP) is identified, which utilizes UDP port 123.

NTP requires fast, connectionless delivery over UDP to calculate clock offsets without TCP handshake latency.

Identify the required service for sending asynchronous event notifications.

SNMP Trap delivery is identified, which operates over UDP port 162.

Managed devices push asynchronous trap messages to the SNMP manager on UDP port 162 (whereas standard SNMP queries use UDP port 161).

Select the correct protocol options matching these requirements.

UDP port 123 and UDP port 162 are selected.

Both NTP time synchronization and SNMP traps utilize UDP as their transport layer protocol.

Key Concept

Standard Well-Known Ports for Network Management (NTP and SNMP Traps)

Question 13Question →

A network administrator is configuring a dedicated IPv4 subnet for a high-availability database cluster. The cluster requires static IP address assignments for 14 active database nodes, 2 redundant monitoring interfaces, and 1 default gateway router interface. Which subnet mask provides the minimum host capacity required to accommodate all devices while conserving IP address space?

255.255.255.240

255.255.255.224

255.255.255.192

255.255.255.248

Show answer & explanation

Answer: 255.255.255.224

Answer

The subnet mask 255.255.255.224 provides the smallest usable host capacity (30 host addresses) that accommodates the 17 required host IP assignments.

The scenario requires 17 usable IP addresses (14 nodes + 2 monitoring + 1 default gateway). The formula for usable hosts in a subnet is 2^(32 - prefix length) - 2. A /27 subnet mask (255.255.255.224) has 5 host bits, providing 2^5 - 2 = 30 usable host IP addresses, which is the smallest standard IPv4 block capable of holding 17 hosts.

Step-by-Step Solution

Calculate the total number of usable host IP addresses required for the cluster.

14 database nodes + 2 monitoring interfaces + 1 gateway interface = 17 usable host IP addresses required.

Every active host and interface requiring an IP on the subnet must be counted towards the total host address requirement.

Determine the minimum block size needed by accounting for network and broadcast addresses.

Total IP addresses needed = 17 hosts + 1 network address + 1 broadcast address = 19 IP addresses minimum.

IPv4 subnets require 2 unassignable addresses: the network ID (all host bits 0) and the broadcast address (all host bits 1).

Find the smallest power of 2 greater than or equal to the total required IP addresses.

2^5 = 32 total IP addresses (which allows 32 - 2 = 30 usable hosts).

Block sizes in IPv4 CIDR subnetting must be powers of 2. A block of 16 (2^4) yields only 14 usable hosts, which is insufficient.

Convert the required block size to a dotted-decimal subnet mask.

32 - 5 host bits = 27 network bits (/27 prefix). In dotted-decimal format, 255.255.255.224.

A prefix length of /27 leaves 5 host bits, corresponding to a last octet value of 256 - 32 = 224.

Key Concept

IPv4 Subnet Mask Capacity and Usable Host Calculation

Question 14Question →

Match each network classification or physical/logical topology on the left with its corresponding architectural design characteristic on the right.

Click a left item, then click its matching right item

Show answer & explanation

Answer

Storage Area Network (SAN) matches with 'Dedicated high-speed network providing block-level storage access to servers using specialized storage protocols.' Campus Area Network (CAN) matches with 'Network connecting multiple distinct local area networks across adjacent buildings within a contiguous geographical boundary.' Full Mesh Topology matches with 'Redundant layout where every node maintains a direct point-to-point connection to every other node, maximizing fault tolerance.' Logical Bus Topology matches with 'Data transmission arrangement where all nodes share a common broadcast medium and single collision domain regardless of physical wiring.'

Each network concept is correctly paired with its specific operational scope and structural characteristic: SAN for block-level storage networking, CAN for multi-building contiguous campus connections, Full Mesh for complete point-to-point node redundancy, and Logical Bus for shared broadcast/collision domain behavior.

Step-by-Step Solution

Analyze storage-specific network architectures.

Identified Storage Area Network (SAN) as the dedicated network designed for block-level storage transfer.

SANs isolate storage traffic from enterprise LAN traffic using protocols like Fibre Channel or iSCSI.

Differentiate geographic network scopes.

Identified Campus Area Network (CAN) as the link between multiple LANs across contiguous corporate or university buildings.

CAN scope is larger than a single LAN but smaller and more geographically unified than a Metropolitan Area Network (MAN).

Evaluate high-availability physical topologies.

Matched Full Mesh Topology to the design requiring direct connections between all node pairs.

Full mesh formula n(n-1)/2 calculates total required links ensuring maximum redundancy.

Distinguish physical wiring from logical traffic flow.

Matched Logical Bus Topology to shared medium access and single collision domain behavior.

Logical topology defines electrical signal path and media access rules independently of physical cabling arrangement.

Key Concept

Network Topologies and Geographic Classifications

Estimated Time:1m 30s

Question 15Question →

A network engineer is provisioning subnets from the assigned IPv4 block $10.150.12.0/22$ for an industrial automation network. Each production segment requires a subnet capable of accommodating at least $110$ usable IP addresses for automated controllers and monitoring sensors. What is the maximum number of subnets meeting this requirement that can be created from the allocated block?

Show answer & explanation

Answer: 8

Answer

The maximum number of valid subnets that can be created is 8.

To host at least

110

usable IP addresses per segment,

7

host bits are required because

2^7 - 2 = 126

usable host IPs (

6

bits only provide

2^6 - 2 = 62

usable IPs). A

7

-bit host field corresponds to a

/25

prefix length (

32 - 7 = 25

). Subnetting a

/22

block into

/25

subnets yields

2^{25 - 22} = 2^3 = 8

subnets.

Step-by-Step Solution

Calculate the host bits needed for at least 110 usable IP addresses.

7 host bits are required because

2^7 - 2 = 126

usable hosts (

2^6 - 2 = 62

is insufficient).

Each subnet must accommodate 110 hosts, requiring 7 host bits.

Determine the required prefix length for each subnet.

Subnet prefix length is

/25

(

32 - 7 = 25

Subtracting host bits from 32 gives the network prefix length.

Determine the number of

/25

subnets created from a

/22

block.

2^{(25 - 22)} = 2^3 = 8

subnets.

The difference between the new prefix length (/25) and original prefix length (/22) provides 3 subnet bits.

Key Concept

Subnet sizing and host capacity calculation using IPv4 CIDR notation

Question 16Question →

A network systems engineer is configuring edge firewall access control lists (ACLs) to allow administrators to deploy a secure web management portal that authenticates domain users against an encrypted centralized directory server. Which TWO of the following port and transport protocol combinations must be permitted through the firewall to support these services? (Select TWO.)

Select all that apply

TCP 443

TCP 636

UDP 636

TCP 389

Show answer & explanation

Answer: TCP 443; TCP 636

Answer

The firewall must permit TCP port 443 for HTTPS web access and TCP port 636 for secure LDAPS directory service authentication.

The scenario requires permitting secure web portal traffic (HTTPS) and encrypted directory authentication (LDAPS). HTTPS relies on TCP port 443 for TLS-encrypted communication. LDAPS relies on TCP port 636 to secure directory queries over TLS. Therefore, permitting TCP 443 and TCP 636 fulfills all secure connectivity requirements.

Step-by-Step Solution

Identify the required secure web service protocol and its default transport port.

Secure web management uses HTTPS, which operates over TCP port 443.

HTTPS uses TLS encryption on connection-oriented TCP port 443.

Identify the required secure directory service authentication protocol and its default transport port.

Encrypted directory authentication uses LDAPS, which operates over TCP port 636.

LDAPS provides encrypted access to directory services over TLS on TCP port 636.

Evaluate transport layer protocol and port number requirements against invalid options.

Rule out UDP port 636 and TCP port 389.

LDAPS requires TCP for reliable connection management (ruling out UDP), and standard unencrypted LDAP uses port 389 rather than port 636.

Key Concept

Common Secure Network Ports and Protocols (HTTPS and LDAPS)

Question 17Question →

A system administrator is configuring static IP addresses for IoT monitoring sensors within a subnet assigned the network address block $192.168.88.0/26$ . Which of the following IP addresses is a valid usable host address for a sensor in this subnet?

192.168.88.45

192.168.88.0

192.168.88.63

192.168.88.64

Show answer & explanation

Answer: $192.168.88.45$

Answer

The IP address

192.168.88.45

is a valid usable host address within the

192.168.88.0/26

subnet.

For a

/26

prefix, the total number of addresses in the subnet is

2^{32-26} = 64

. The address block spans from

192.168.88.0

192.168.88.63

. Subtracting the network address (

192.168.88.0

) and the broadcast address (

192.168.88.63

) yields a usable host range of

192.168.88.1

through

192.168.88.62

. The value

192.168.88.45

falls within this valid range.

Step-by-Step Solution

Determine the block size from the CIDR prefix length

/26

prefix uses

32 - 26 = 6

host bits. The total block size is

2^6 = 64

addresses.

Calculating the total number of addresses per block establishes the subnet boundary.

Calculate the network ID and broadcast address

The network address is

192.168.88.0

. The broadcast address is

192.168.88.0 + 64 - 1 = 192.168.88.63

The first address in the block is the network ID and the last address is the broadcast address.

Identify the range of usable host IP addresses

Usable host range is from

192.168.88.1

(first usable) to

192.168.88.62

(last usable).

Usable host IPs exclude the network ID and the broadcast address.

Evaluate the given choices against the usable host range

The address

192.168.88.45

is the only candidate that falls strictly between

192.168.88.1

and

192.168.88.62

Only addresses within the usable host range can be assigned to host devices.

Key Concept

IPv4 Usable Host Addressing in CIDR Subnets

Question 18Question →

During a packet capture analysis on a receiving web server, a network technician traces an incoming Ethernet frame carrying an HTTP request. As the server's network stack begins de-encapsulating the data, the Network Interface Card (NIC) verifies the Frame Check Sequence (FCS) and strips the Layer 2 Ethernet header and trailer. Which Protocol Data Unit (PDU) is immediately passed up to the Network layer (Layer 3) for further processing?

Packet

Segment

Frame

Data Payload

Show answer & explanation

Answer: Packet

Answer

The Protocol Data Unit passed to Layer 3 is the Packet.

During de-encapsulation on an incoming host, the network stack processes data from the bottom up. The Data Link layer (Layer 2) processes the Ethernet Frame, checks for transmission errors using the trailer's Frame Check Sequence (FCS), and strips the Ethernet header and trailer. The payload remaining is an IP Packet, which is handed directly to the Network layer (Layer 3) to examine source and destination IP addresses.

Step-by-Step Solution

Identify the initial receiving layer and PDU

The receiving host receives physical signals and reconstructs a Layer 2 Frame.

The Ethernet protocol operates at Layer 2 (Data Link layer).

Perform Layer 2 de-encapsulation

The Layer 2 Ethernet header and trailer (FCS) are inspected and removed.

De-encapsulation unwraps outer headers to expose the inner payload.

Determine the resulting PDU passed to Layer 3

The remaining inner payload is an IP Packet.

Layer 3 (Network layer) operates on Packets containing IP addressing information.

Key Concept

OSI De-encapsulation Sequence and Layer PDUs

Estimated Time:1m 0s

Question 19Question →

A software developer and a network technician are configuring a bulk database migration utility across an enterprise link. The application establishes communication channels between two servers, maintains dialog control between the endpoints, and places synchronization checkpoints within the data stream so that interrupted file transfers can resume from the last saved state without starting over. Which layer of the OSI model is directly responsible for managing these dialog control and checkpoint synchronization functions?

Transport Layer

Session Layer

Presentation Layer

Network Layer

Show answer & explanation

Answer: Session Layer

Answer

Session Layer

The Session Layer (Layer 5) of the OSI model is dedicated to establishing, maintaining, synchronizing, and terminating communication sessions between applications. Key duties include dialog control (determining half-duplex or full-duplex communication modes) and inserting checkpoints into data streams to facilitate recovery from communication failures.

Step-by-Step Solution

Analyze the core requirements in the scenario

Identified session management, dialog control, and checkpoint insertion as the key functional requirements.

The question asks to identify which OSI layer handles these specific services.

Map requirements to OSI layer responsibilities

Layer 5 (Session Layer) explicitly defines dialog control (managing which side transmits and when) and session synchronization (setting checkpoints for failure recovery).

Other layers handle syntax translation (Presentation), transport reliability (Transport), or packet routing (Network).

Key Concept

OSI Model Session Layer (Layer 5) Functions

Estimated Time:1m 0s

Question 20Question →

A network engineer is analyzing the convergence behavior of a core enterprise router running Open Shortest Path First (OSPF). An active link on an adjacent network interface suddenly fails, triggering a topology update across the area. Place the operational steps in the correct sequential order from initial failure detection to final packet forwarding updates.

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct sequence for OSPF link-state convergence is: 1) Generate LSA upon failure detection, 2) Flood LSA to neighbors, 3) Update local LSDB with new information, 4) Run SPF algorithm on updated LSDB, and 5) Populate the IP routing table with recalculated optimal paths.

OSPF is a link-state routing protocol operating in distinct sequential phases during topology changes. When a link fails, the detecting router immediately originates a new Link-State Advertisement (LSA). This LSA is flooded out active interfaces to ensure area-wide synchronization. Upon receiving the LSA, neighboring routers insert it into their Link-State Database (LSDB). Once the LSDB reflects the true network state, each router executes Dijkstra's Shortest Path First (SPF) algorithm to calculate the new shortest path tree. Finally, the newly derived best paths are installed into the router's IP routing table for packet forwarding.

Step-by-Step Solution

Identify event detection and LSA origination

The local router detects physical/logical link failure and creates an updated LSA.

Routing convergence begins at the source router where the topology change occurs.

Identify LSA propagation

The originating router floods the LSA across the OSPF area using multicast.

Link-state protocols require all routers in an area to maintain identical database records.

Identify LSDB synchronization

Neighboring routers update their local LSDBs with the received LSA.

The database must reflect the updated network map before path selection can take place.

Identify path recalculation

Dijkstra's SPF algorithm computes shortest paths based on the new LSDB state.

SPF uses the synchronized topology map to find optimal cost paths to every destination subnet.

Identify Routing Information Base (RIB) modification

The router installs the newly derived shortest paths into the active IP routing table.

Packet forwarding decisions rely directly on the active routing table entries derived from SPF calculation.

Key Concept

OSPF Link-State Convergence and SPF Calculation Sequence

Estimated Time:2m 0s

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