CompTIA Network+ — All Questions

Which PoE standard delivers the most power, up to about 90 W at the source, for devices like PTZ cameras and displays?

• a.802.3u Fast Ethernet
• b.802.3bt (PoE++)✓
• c.802.3af (PoE)
• d.802.3at (PoE+)

802.3bt, known as PoE++, supplies up to roughly 90 W at the source across all four pairs, powering high-draw devices. 802.3af provides about 15 W and 802.3at about 30 W. 802.3u is a Fast Ethernet standard, unrelated to power delivery.

Which switch configuration forces a port to operate as a trunk regardless of the neighbor's negotiation settings?

• a.switchport nonegotiate off
• b.switchport mode trunk✓
• c.no switchport
• d.switchport mode access

The command switchport mode trunk statically sets the port to trunk, carrying tagged VLAN traffic without relying on dynamic negotiation. switchport mode access fixes it as an access port. Hard-setting trunk mode avoids issues from mismatched auto-negotiation.

Enabling jumbo frames on a storage network changes which interface setting to roughly 9000 bytes?

• a.The VLAN ID
• b.The maximum transmission unit (MTU)✓
• c.The spanning-tree cost
• d.The administrative distance

Jumbo frames raise the interface MTU to about 9000 bytes so large payloads move with less per-packet overhead, benefiting iSCSI and backup traffic. Every device in the path must support the same larger MTU. A mismatch causes fragmentation or dropped frames.

Disabling SSID broadcast on an access point has which practical effect?

• a.It hides the network name from casual scans but not from determined attackers✓
• b.It encrypts all wireless traffic automatically
• c.It doubles the available bandwidth
• d.It prevents all deauthentication attacks

Hiding the SSID stops the name from appearing in ordinary device scans but does not provide real security, since the SSID still travels in other frames and tools can reveal it. It offers no encryption and does not stop skilled attackers. Strong encryption like WPA3 is the actual protection.

Which feature presents a web page requiring acceptance of terms or login before granting guests wireless internet access?

• a.MAC randomization
• b.Band steering
• c.WPA3-Enterprise
• d.Captive portal✓

A captive portal intercepts a new client's web traffic and forces it to a page for authentication or acceptance of terms before allowing access. It is common on guest and public Wi-Fi. It controls access without distributing a shared passphrase.

For seamless roaming as a user walks between two access points, how should the APs be configured?

• a.Hidden SSIDs with static client IPs
• b.Different SSIDs and the same channel
• c.The same SSID on non-overlapping channels✓
• d.The same SSID and the same channel

Seamless roaming needs the same SSID across APs so clients see one network, with each AP on a non-overlapping channel to avoid co-channel interference. Matching channels would cause interference in overlapping coverage. Consistent security settings are also required for smooth handoff.

In a router's table, which route source has the most trustworthy administrative distance of 0?

• a.Static routes
• b.RIP-learned routes
• c.Directly connected interfaces✓
• d.OSPF-learned routes

Directly connected networks have an administrative distance of 0, the most trusted, because the router has a live interface on that network. Static routes default to 1, OSPF to 110, and RIP to 120. Lower administrative distance always wins when routes overlap.

When configuring router-on-a-stick, what must be applied to each subinterface for it to service a specific VLAN?

• a.An 802.1Q encapsulation tag matching the VLAN ID✓
• b.A separate physical NIC per VLAN
• c.An access-list that permits any
• d.A crossover cable to the switch

Each router subinterface must be configured with 802.1Q encapsulation for the specific VLAN ID so it can send and receive tagged frames on the trunk. The switch port to the router is configured as a trunk. This lets one physical link route among many VLANs.

Which device combines high-speed hardware switching with the ability to route between VLANs using ASICs?

• a.A media converter
• b.A wireless controller
• c.A Layer 3 (multilayer) switch✓
• d.An unmanaged hub

A Layer 3 or multilayer switch performs both switching and routing in hardware, routing between VLANs at wire speed via switched virtual interfaces. This outperforms router-on-a-stick for high inter-VLAN traffic. It is the standard core and distribution device in campus networks.

Which feature shuts down a PortFast-enabled access port if it unexpectedly receives a BPDU, protecting the spanning-tree topology?

• a.Storm control
• b.BPDU guard✓
• c.Root guard
• d.DHCP snooping

BPDU guard disables a PortFast access port the moment it receives a BPDU, since that indicates an unauthorized switch was connected. This protects the topology from accidental loops or rogue switches. It is commonly paired with PortFast on edge ports.

Which open-standard first-hop redundancy protocol lets multiple routers share a virtual IP so hosts keep a single default gateway?

• a.OSPF
• b.STP
• c.VRRP✓
• d.LACP

Virtual Router Redundancy Protocol (VRRP) is an open standard that lets multiple routers present one virtual gateway IP, with a backup taking over if the master fails. HSRP is a Cisco equivalent. This removes the default gateway as a single point of failure.

Before deploying wireless in a warehouse, which activity maps signal strength and identifies interference and coverage gaps?

• a.A port scan
• b.A cable certification test
• c.A packet capture
• d.A wireless site survey✓

A wireless site survey measures signal strength, interference, and coverage across the space, guiding AP placement, channel plans, and power levels. It produces heat maps that reveal dead zones before deployment. Skipping it often leads to coverage and roaming problems.

An administrator wants the DHCP scope to skip .1 through .10 because those are statically assigned to servers. Which setting accomplishes this?

• a.A reservation
• b.An exclusion range✓
• c.A shorter lease time
• d.A relay agent

An exclusion range removes specific addresses from the DHCP pool so they are never leased, protecting statically assigned server addresses. A reservation, by contrast, hands a fixed address to a particular device via DHCP. Exclusions prevent address conflicts with manual assignments.

How does a switch build its MAC address table?

• a.By recording the source MAC and ingress port of frames it receives✓
• b.By copying the routing table from the gateway
• c.By querying DNS for each destination host
• d.By broadcasting ARP on every port at boot

A switch learns by examining the source MAC address of incoming frames and associating it with the port they arrived on. It then forwards frames only to the known port for a destination, flooding only when the destination is unknown. Entries age out after a period of inactivity.

In the static route 'ip route 192.168.50.0 255.255.255.0 10.0.0.2', what does 10.0.0.2 represent?

• a.The subnet mask
• b.The administrative distance
• c.The next-hop address✓
• d.The destination network

In that command, 192.168.50.0 is the destination network, 255.255.255.0 is its mask, and 10.0.0.2 is the next-hop IP to which matching traffic is forwarded. The router sends packets for that network toward 10.0.0.2. An optional trailing number would set the administrative distance.

In OSPF, which area must all other areas connect to, acting as the backbone?

• a.The not-so-stubby area
• b.Area 1
• c.The stub area
• d.Area 0✓

OSPF designates Area 0 as the backbone, and all other areas must connect to it, directly or via virtual links, so inter-area routing passes through the backbone. This hierarchy keeps the topology scalable and loop-free. Stub and NSSA areas are special non-backbone area types.

A 370 W PoE switch cannot power the 30th camera even though ports are free. What has most likely been exceeded?

• a.The DHCP scope
• b.The MAC address table size
• c.The spanning-tree diameter
• d.The switch's total PoE power budget✓

Each PoE switch has a finite power budget shared across all ports, and adding devices can exhaust it even when physical ports remain. The switch then stops powering additional devices. The fix is a higher-wattage power supply or a switch with a larger PoE budget.

Traffic for VLAN 40 is not crossing a trunk, though VLAN 40 exists on both switches. Which trunk setting should be checked first?

• a.The port speed and duplex
• b.The list of VLANs allowed on the trunk✓
• c.The PoE class of the port
• d.The DNS server address

Trunks can be configured to allow only specific VLANs, so VLAN 40 may simply be missing from the allowed list on the trunk. Verifying and adding it to the allowed VLANs restores the traffic. Native VLAN mismatches are another common trunking issue to check.

Which wireless security mode authenticates each user against a central RADIUS server rather than a shared passphrase?

• a.WPA3-Personal
• b.WEP
• c.WPA3-Enterprise✓
• d.Open with MAC filtering

WPA3-Enterprise uses 802.1X with a RADIUS server so each user authenticates with unique credentials rather than one shared key. This enables per-user access control and easy revocation. Personal modes rely on a single pre-shared key for everyone.

Which is the correctly compressed form of 2001:0db8:0000:0000:0000:0000:0000:0001?

• a.2001:db8::1✓
• b.2001:db8:0:1
• c.2001:0db8::0001::
• d.2001:db8:::1

Leading zeros in each group are dropped and one run of all-zero groups is replaced by a single double colon, giving 2001:db8::1. The double colon may appear only once in an address. Two double colons or an incomplete result would be invalid.