D-NWG-FN-23 Dell Networking Foundations Practice Questions
Prepare for D-NWG-FN-23 with more than an answer.
- Level
- Foundation
Domains covered on the exam 7
- Networking Essentials5%
- Ethernet Technologies40%
- IP Networking25%
- Network Services5%
- Security Essentials10%
- Network Operations10%
- Automation5%
- 1
A network administrator is given the IP address 192.168.50.133 and a subnet mask of 255.255.255.224. What is the broadcast address for this subnet?
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Correct answer: B
A subnet mask of 255.255.255.224 (/27) has a block size of 32 (256-224=32). The subnets are .0, .32, .64, .96, .128, .160, etc. The IP address 192.168.50.133 falls into the subnet that starts at 192.168.50.128. The next subnet starts at .160, so the broadcast address for the .128 subnet is the address just before that, which is 192.168.50.159.
- 2
According to IPv6 address compression rules, which is the correct way to shorten the address 2001:0db8:0000:0000:a1b2:00ff:fe34:5678?
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Correct answer: A
IPv6 compression rules allow two things: 1) removing leading zeros in each hextet, and 2) using a double colon (::) once to represent the longest consecutive string of all-zero hextets. In this address, '0db8' becomes 'db8', the two '0000' hextets become '::', and '00ff' becomes 'ff'. This results in 2001:db8::a1b2:ff:fe34:5678.
- 3
A Layer 3 switch has the following routes in its routing table:
- 10.10.0.0/16
- 10.10.20.0/24
- 10.10.20.128/25
If the switch receives a packet destined for the IP address 10.10.20.150, which route will it use to forward the packet?
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Correct answer: C
Routers and Layer 3 switches use the 'longest prefix match' rule to determine the best route. The destination IP 10.10.20.150 matches all three routes. However, the /25 prefix is the most specific (longest) match. The /16 matches the first 16 bits, the /24 matches the first 24 bits, and the /25 matches the first 25 bits. Therefore, the most specific route, 10.10.20.128/25, will be chosen.
graph TD A[Packet for 10.10.20.150] --> B{Routing Table Lookup} B --> C{Match 10.10.0.0/16?} C -->|Yes| D{Match 10.10.20.0/24?} D -->|Yes| E{Match 10.10.20.128/25?} E -->|Yes| F[Forward via /25 route] C -->|No| G[Drop/Default Route] D -->|No| H[Forward via /16 route] E -->|No| I[Forward via /24 route] - 4
In which scenario would a network administrator most likely choose to configure static routes instead of a dynamic routing protocol?
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Correct answer: B
Static routing is ideal for simple, predictable network topologies, such as a stub network (a network with only one exit point). Since there is only one way out, there is no need for the complexity and overhead of a dynamic routing protocol. A single static default route pointing to the exit is sufficient and efficient.
- 5
A retail company has deployed Dell PowerSwitch switches in its stores. Each store has several VLANs, including one for guest Wi-Fi (VLAN 50) and one for corporate devices (VLAN 20). The company uses a centralized DHCP server located at its data center to assign IP addresses. The local switch in the store is connected to the data center via a WAN link.
When a guest connects to the Wi-Fi, their device sends a DHCP Discover broadcast. This broadcast needs to reach the centralized DHCP server. The store switch is a Layer 3 capable switch with SVI's for each VLAN.
What must be configured on the store switch to allow guest devices to obtain an IP address from the central DHCP server?
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Correct answer: C
DHCP requests are broadcast messages, which are not forwarded by routers or Layer 3 switches by default. The IP helper-address (or DHCP relay) feature is designed for this scenario. When configured on a Layer 3 interface (like a VLAN SVI), it intercepts DHCP broadcast packets and forwards them as unicast packets to the specified DHCP server IP address, allowing clients to get IP addresses from a DHCP server on a different subnet.
- 6
A network team is investigating an issue where log messages from various network devices have inconsistent timestamps, making it difficult to correlate events during a security incident. What network service should be implemented to resolve this problem?
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Correct answer: C
Network Time Protocol (NTP) is used to synchronize the clocks of computers and network devices over a network. By configuring all devices to use a common NTP server, their internal clocks will be synchronized, ensuring that log messages and event timestamps are consistent across the entire infrastructure. This is crucial for accurate troubleshooting and security forensics.
- 7
A security policy requires that all traffic from the guest network (192.168.100.0/24) be prevented from accessing the internal corporate server network (10.10.0.0/16). An administrator needs to create an access control list (ACL) on the router interface connected to the guest network. Which type of ACL is most appropriate for this task?
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Correct answer: B
The requirement is to filter traffic based on both the source IP address (guest network) and the destination IP address (corporate network). Standard ACLs can only filter based on the source IP address. Extended ACLs are required because they can inspect source IP, destination IP, protocol type, and port numbers, providing the necessary granularity to enforce this policy.
- 8
A network technician is connecting two Dell PowerSwitch switches in different wiring closets that are 150 meters apart. The connection must support a minimum of 10 Gbps. Which cabling and transceiver combination is the most appropriate and cost-effective solution for this requirement?
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Correct answer: B
For a distance of 150 meters at 10 Gbps, multi-mode fiber is the correct choice. 10GBASE-SR transceivers using OM3 multi-mode fiber can support distances up to 300 meters. Cat6a copper is limited to 100 meters. Single-mode fiber is capable of much longer distances but is typically more expensive and unnecessary for 150 meters. DAC cables are for very short distances, usually within a single rack.
- 9
During the initial setup of a new Dell PowerSwitch, a junior administrator configures the management IP address, subnet mask, and hostname. After saving the configuration and connecting the switch to the network, the administrator cannot ping the switch from their workstation on a different subnet. What is the most likely missing configuration step?
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Correct answer: C
For a device to communicate with other devices outside of its own subnet, it needs a default gateway. The default gateway is the IP address of the router interface that the switch will send all traffic destined for remote networks to. Without it, the switch does not know how to reply to the ping from a different subnet.
- 10
A network monitoring tool reports continuous MAC address flapping for a specific MAC address between port ethernet1/1/1 on Switch-A and port ethernet1/1/2 on Switch-B. What is the most probable cause of this issue?
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Correct answer: C
MAC address flapping is a classic symptom of a Layer 2 switching loop. This occurs when there are redundant paths between switches and Spanning Tree Protocol (STP) is disabled or misconfigured. The switches continuously update their MAC address tables, associating the same MAC address with different ports as broadcast frames loop endlessly through the network.
