When a new VLAN is created, it typically exists on a different subnet. If DHCP servers are on a different VLAN, the network needs an IP helper address to forward DHCP requests correctly. Without it, clients in the new VLAN won't receive an IP address.
Breakdown of Options:
A: Scope size - Increasing the DHCP scope would not resolve the issue if requests aren't reaching the server.
B: Address reservations - Reservations only assign specific addresses to devices; they do not fix DHCP communication issues.
C: Lease time - Changing the lease time does not impact DHCP functionality across VLANs.
D: IP helper - Correct answer. This forwards DHCP requests across VLANs to the DHCP server.
Reference:
CompTIA Network+ (N10-009) Official Study Guide - Domain 2.4: Explain IP addressing technologies and subnetting.
RFC 1542: BOOTP (Bootstrap Protocol) relay agents

The issue is clearly related toDNS resolution, as IP-based connections succeed but domain name-based ones fail.
* D. dig(Domain Information Groper) is a DNS lookup tool used to troubleshoot DNS problems by querying name servers directly.
Other tools are less relevant here:
* A. tcpdumpis a packet analyzer and is more advanced for deeper traffic analysis.
* B. tracertis used to trace the route to a destination, not ideal for DNS issues.
* C. nmapis a port scanner and network mapper, not for resolving DNS problems.
#Reference:
CompTIA Network+ N10-009 Official Objectives: 5.1 - Given a scenario, use the appropriate network troubleshooting tools.

Link Layer Discovery Protocol (LLDP) is a network protocol used for discovering devices and their capabilities on a local area network, primarily at the data link layer (Layer 2). It helps in identifying the connected switch and the specific port to which a device is connected. When troubleshooting a VoIP handset connection, the technician can use LLDP to determine the exact switch and port where the handset is connected. This protocol is widely used in network management to facilitate the discovery of network topology and simplify troubleshooting.
Other options such as IKE (Internet Key Exchange), VLAN (Virtual LAN), and netstat (network statistics) are not suitable for identifying the switch and port information. IKE is used in setting up secure IPsec connections, VLAN is used for segmenting networks, and netstat provides information about active connections and listening ports on a host but not for discovering switch port details.
Reference: CompTIA Network+ Certification Exam Objectives - Network Troubleshooting and Tools section.

Band Steering: This technology enables wireless devices to connect to the most optimal frequency band (2.4 GHz or 5 GHz) by encouraging capable devices to switch to the less congested 5 GHz band. This improves overall network performance and prevents overcrowding on the 2.4 GHz band.
Wireless LAN controller (B): This manages multiple access points in a network but does not handle frequency optimization.
Directional antenna (C): This focuses the signal in a specific direction but does not affect frequency selection.
Autonomous access point (D): This operates independently but lacks advanced features like band steering.
Reference: CompTIA Network+ Official Study Guide, Domain 1.6 (Wireless Standards and Technologies).