CompTIA Network+ — All Questions

Which TCP port carries LDAP directory traffic secured with SSL or TLS as LDAPS?

• a.989
• b.636✓
• c.389
• d.443

LDAPS encrypts directory traffic and uses TCP port 636. Standard LDAP on 389 is unencrypted. Port 443 is HTTPS and 989 is FTPS data, so neither applies to secure directory queries.

Which port is used by unencrypted SIP for setting up and tearing down VoIP calls?

• a.5060✓
• b.5061
• c.1720
• d.554

SIP signaling for VoIP call setup and teardown uses port 5060 without encryption, while 5061 is used for SIP over TLS. Port 1720 is H.323 and 554 is RTSP for streaming. SIP handles signaling while RTP carries the actual media.

Which TCP port does POP3 use to download email, typically removing it from the server?

• a.143
• b.110✓
• c.465
• d.25

POP3 uses TCP port 110 and generally downloads messages to a single device, removing them from the server. IMAP on 143 keeps mail synchronized on the server. Secure POP3 over TLS uses port 995.

Which port does Kerberos use for authentication in Windows Active Directory environments?

• a.636
• b.88✓
• c.445
• d.389

Kerberos authentication uses port 88 to issue and validate tickets in Active Directory. LDAP uses 389, LDAPS 636, and SMB 445 in the same environments. Kerberos provides single sign-on through its ticket-granting mechanism.

Which TCP port carries unencrypted HTTP web traffic by default?

• a.21
• b.80✓
• c.8080
• d.443

HTTP uses TCP port 80 for unencrypted web traffic. Port 443 carries HTTPS with TLS encryption, and 8080 is a common alternate proxy or web port. Modern sites redirect port 80 to 443 for security.

Which default TCP port does Microsoft SQL Server listen on for database client connections?

• a.3306
• b.1521
• c.1433✓
• d.5432

Microsoft SQL Server listens on TCP port 1433 by default. MySQL uses 3306, Oracle 1521, and PostgreSQL 5432. Database ports should be restricted to application servers rather than exposed broadly.

Which sequence correctly lists the four DHCP messages a client and server exchange to obtain a lease?

• a.Offer, Discover, Acknowledge, Request
• b.Discover, Request, Offer, Acknowledge
• c.Discover, Offer, Request, Acknowledge✓
• d.Request, Offer, Discover, Acknowledge

The DHCP process follows the DORA sequence: the client broadcasts a Discover, the server sends an Offer, the client sends a Request for the offered address, and the server confirms with an Acknowledge. Remembering DORA keeps the order straight. Only after the ACK does the client use the leased address.

Which DNS record type maps a hostname to an IPv4 address?

• a.CNAME
• b.MX
• c.AAAA
• d.A✓

The A record maps a hostname to a 32-bit IPv4 address. The AAAA record does the same for IPv6, MX points to mail servers, and CNAME creates an alias. A records are the most common forward-lookup entries.

Which DNS record type resolves a hostname to an IPv6 address?

• a.PTR (reverse pointer)
• b.TXT
• c.A
• d.AAAA✓

The AAAA (quad-A) record maps a hostname to a 128-bit IPv6 address. The A record handles IPv4, PTR handles reverse lookups, and TXT holds arbitrary text. Dual-stack hosts commonly have both A and AAAA records.

Which DNS record identifies the mail server responsible for accepting email for a domain?

• a.CNAME
• b.MX✓
• c.SRV
• d.NS

The MX (Mail Exchange) record specifies the mail servers that accept email for a domain, along with a priority value. Lower priority numbers are preferred. SRV records locate other services, while NS records delegate the zone.

Which DNS record creates an alias that points one hostname to another canonical name?

• a.CNAME✓
• b.PTR
• c.SOA
• d.A

A CNAME (Canonical Name) record aliases one hostname to another, so www can point to a canonical host that itself has an A record. It avoids duplicating address records. A CNAME should not coexist with other record types for the same name.

Which DNS record maps an IP address back to a hostname for reverse lookups?

• a.TXT
• b.A
• c.PTR✓
• d.MX

The PTR (pointer) record provides reverse DNS, mapping an IP address to a hostname within the in-addr.arpa or ip6.arpa zones. Mail servers often check PTR records to help verify sender legitimacy. It is the inverse of an A or AAAA record.

Which DNS record type holds free-form text and is used for SPF, DKIM, and domain-verification data?

• a.SRV
• b.CNAME
• c.TXT✓
• d.NS

The TXT record stores arbitrary text and is widely used for email authentication such as SPF and DKIM, plus domain ownership verification. It carries policy data rather than addressing. Its flexibility makes it central to modern email security.

In a DNS record, what does the TTL value control?

• a.How long a resolver may cache the record✓
• b.The priority of a mail server
• c.The UDP port the query is sent to
• d.The maximum size of the DNS response packet

The DNS TTL tells resolvers how many seconds they may cache a record before querying again for a fresh copy. Lower TTLs speed propagation of changes but increase query load. Administrators lower TTLs before planned changes to reduce stale answers.

Which term describes a DNS resolver that takes full responsibility for querying other servers and returning a final answer to the client?

• a.Root hint server
• b.Authoritative-only server
• c.Iterative forwarder
• d.Recursive resolver✓

A recursive resolver accepts a client's query and does the work of contacting root, TLD, and authoritative servers until it has the final answer. The client makes one request and gets one answer. Authoritative servers, by contrast, only answer for the zones they host.

In NTP, what does the stratum number indicate?

• a.The distance in hops from a reference clock✓
• b.The encryption strength of the time source
• c.The UDP port used for synchronization
• d.The number of clients a server can serve

The NTP stratum indicates how many steps a time source is from an authoritative reference clock, with stratum 0 being the reference itself and stratum 1 directly attached. Higher stratum numbers are further away and slightly less accurate. Clients typically sync to low-stratum servers.

Which DHCP feature guarantees that a specific device always receives the same IP address based on its MAC address?

• a.Exclusion range
• b.Lease time
• c.Scope option
• d.Reservation✓

A DHCP reservation ties a specific MAC address to a fixed IP so the device always gets the same address while still using DHCP. Exclusions merely remove addresses from the pool, and scope options set parameters like DNS. Reservations suit printers and servers that need consistent addressing.

On which UDP port does NTP exchange time-synchronization messages?

• a.53
• b.67
• c.514
• d.123✓

NTP uses UDP port 123 to synchronize clocks between devices and time sources. Port 53 is DNS, 67 is DHCP, and 514 is syslog. Accurate time from NTP underpins logging, certificates, and authentication.

Which UDP port pair does DHCP use for server and client communication?

• a.80 and 8080
• b.53 and 54
• c.67 and 68✓
• d.137 and 138

DHCP servers listen on UDP port 67 and clients receive on UDP port 68. These ports are essential to allow through firewalls or configure in DHCP relays. Knowing them helps diagnose why clients fail to obtain addresses.

Which DNS record identifies the authoritative name servers for a zone?

• a.MX
• b.PTR
• c.NS✓
• d.A

NS (Name Server) records list the authoritative name servers for a zone and are used to delegate subdomains. MX points to mail servers, PTR handles reverse lookups, and A maps names to IPv4 addresses. Correct NS records are essential for delegation to work.

A company uses a web-based email and CRM suite that the provider fully manages, with no OS or application maintenance by the customer. Which cloud model is this?

• a.PaaS
• b.DaaS
• c.IaaS
• d.SaaS✓

Software as a Service (SaaS) delivers complete, provider-managed applications accessed over the web, with the customer managing only data and users. IaaS and PaaS require the customer to manage more of the stack. Email and CRM suites are classic SaaS examples.

Which cloud service model gives developers a managed platform of runtime, OS, and middleware to deploy their own applications without managing servers?

• a.On-premises
• b.PaaS✓
• c.IaaS
• d.SaaS

Platform as a Service (PaaS) provides a managed environment, including the operating system, runtime, and middleware, so developers deploy code without maintaining the underlying infrastructure. IaaS gives raw compute the customer must manage, and SaaS gives finished apps. PaaS accelerates development.

An organization keeps sensitive workloads in its private data center but bursts to a public provider during peak demand. Which cloud deployment model is this?

• a.Private cloud
• b.Public cloud
• c.Community cloud
• d.Hybrid cloud✓

A hybrid cloud combines private infrastructure with public cloud resources, allowing sensitive workloads to stay private while bursting to public capacity when needed. This balances control with scalability. Cloud bursting is a common hybrid use case.

Which cloud characteristic allows resources to automatically expand and contract in response to changing demand?

• a.Elasticity✓
• b.Multitenancy
• c.Metered billing
• d.Broad network access

Elasticity lets cloud resources scale up during spikes and scale down when demand falls, often automatically. This ensures performance during peaks while avoiding paying for idle capacity. It is a defining advantage of cloud over fixed on-premises hardware.

Which cloud construct provides a logically isolated, customer-defined virtual network with its own subnets and routing inside a public provider?

• a.Network function virtualization (NFV)
• b.Availability zone
• c.Virtual private cloud (VPC)✓
• d.Content delivery network (CDN)

A Virtual Private Cloud (VPC) is a logically isolated section of a public cloud where a customer defines subnets, route tables, and gateways. It gives control similar to an on-premises network within the provider. CDNs cache content, and availability zones describe physical data-center groupings.

RIP considers a route unreachable once its hop count reaches which value?

• a.255
• b.15
• c.16✓
• d.255 milliseconds

RIP treats a hop count of 16 as infinity, meaning the destination is unreachable, so 15 is the maximum number of usable hops. This limit prevents routing loops but also restricts RIP to small networks. Larger networks use OSPF or EIGRP instead.

When a router learns the same destination from two routing protocols, which value determines the preferred source?

• a.MTU size
• b.Hop count
• c.Bandwidth delay product
• d.Administrative distance✓

Administrative distance ranks the trustworthiness of routing sources, so the route from the protocol with the lower administrative distance is installed. For example, OSPF (110) is preferred over RIP (120). Metrics only compare routes within the same protocol.

A router has routes to 10.1.0.0/16 and 10.1.5.0/24 for a packet destined to 10.1.5.10. Which rule decides which route is used?

• a.Longest prefix match✓
• b.Lowest administrative distance
• c.Round-robin load sharing
• d.First route in the table

Routers select the most specific matching route, known as the longest prefix match, so 10.1.5.0/24 wins over 10.1.0.0/16 for that destination. Administrative distance and metrics only break ties among equally specific routes. Longest match always takes precedence first.

Which Cisco-developed routing protocol uses a composite metric and the DUAL algorithm for fast convergence?

• a.OSPF
• b.RIPv2
• c.BGP
• d.EIGRP✓

EIGRP is an advanced distance-vector protocol that uses a composite metric (bandwidth and delay by default) and the DUAL algorithm to precompute backup routes for rapid convergence. OSPF is link-state and BGP is path-vector. EIGRP was historically Cisco-proprietary before being partially opened.

Which routing protocol exchanges reachability between autonomous systems and is the routing protocol of the internet?

• a.BGP✓
• b.EIGRP
• c.OSPF
• d.RIP

Border Gateway Protocol (BGP) is a path-vector protocol that exchanges routing information between autonomous systems and holds the internet's global routing together. OSPF, EIGRP, and RIP are interior gateway protocols used within a single organization. BGP decisions rely on path attributes rather than simple metrics.

Which routing method requires an administrator to manually enter each destination network and next hop, with no automatic reconvergence?

• a.Static routing✓
• b.OSPF routing
• c.Distance-vector routing
• d.Link-state routing

Static routing relies on manually configured entries and does not adapt automatically when a link fails. It is simple and predictable for small or stub networks but does not scale or self-heal. Dynamic protocols like OSPF reconverge automatically after topology changes.

Which category of routing protocol periodically shares its entire routing table with directly connected neighbors and typically uses hop count?

• a.Path-vector
• b.Link-state
• c.Distance-vector✓
• d.Static

Distance-vector protocols like RIP periodically advertise their whole routing table to neighbors and choose paths using simple metrics such as hop count. Link-state protocols instead flood link information and build a full topology map. Distance-vector is simpler but converges more slowly.

A switch port configured to carry traffic for exactly one VLAN to an end device is known as what?

• a.Access port✓
• b.Trunk port
• c.Native port
• d.Mirror port

An access port belongs to a single VLAN and connects to an end device such as a PC or printer, sending untagged frames. A trunk port carries multiple VLANs between switches. Assigning the wrong VLAN to an access port is a common connectivity fault.

Which switch port type carries traffic for multiple VLANs between switches using 802.1Q tagging?

• a.Trunk port✓
• b.Console port
• c.Access port
• d.Loopback port

A trunk port carries frames for many VLANs across a single link, tagging them with 802.1Q so the far end can separate them. Access ports carry only one VLAN. Trunks are essential for extending VLANs between switches and to routers.

How do switches running Spanning Tree Protocol elect the root bridge?

• a.The first switch powered on always wins
• b.The switch with the lowest bridge ID wins✓
• c.The switch with the most ports wins
• d.The switch with the highest IP address wins

STP elects the root bridge as the switch with the lowest bridge ID, which combines a configurable priority value with the MAC address. Lowering a switch's priority makes it the root. The root bridge becomes the reference point for building the loop-free tree.

Which standard improves on classic STP by converging in seconds rather than up to 50 seconds after a topology change?

• a.802.1X
• b.802.1Q
• c.802.3ad
• d.RSTP (802.1w)✓

Rapid Spanning Tree Protocol (RSTP), defined in 802.1w, converges in seconds using proposal and agreement handshakes and new port roles. Classic STP could take up to 50 seconds. RSTP is backward compatible with legacy STP switches.

Which feature lets a single access port carry both a PC's data VLAN and an IP phone's traffic on a separate tagged VLAN?

• a.Management VLAN
• b.Voice VLAN✓
• c.Native VLAN
• d.Private VLAN

A voice VLAN lets a switch port place phone traffic on a dedicated tagged VLAN while the attached PC uses the untagged data VLAN. This separates voice for QoS and security without a second cable. The IP phone typically has a small built-in switch for the PC.

Two hosts are in different VLANs on the same switch and cannot reach each other. What is required to enable their communication?

• a.Placing both ports in the native VLAN
• b.Disabling Spanning Tree Protocol
• c.A Layer 3 device to route between the VLANs✓
• d.A crossover cable between them

VLANs are separate broadcast domains, so traffic between them must be routed by a Layer 3 device such as a router or Layer 3 switch. Simply being on the same physical switch does not allow inter-VLAN communication. A router-on-a-stick or SVI provides this routing.

Which wireless standard is marketed as Wi-Fi 6 and introduces OFDMA to improve efficiency in dense environments?

• a.802.11ax✓
• b.802.11n
• c.802.11ac
• d.802.11g

802.11ax, branded Wi-Fi 6, adds OFDMA and improved MU-MIMO to serve many clients efficiently in congested areas. It operates in both 2.4 and 5 GHz, with Wi-Fi 6E extending into 6 GHz. It boosts real-world throughput in high-density deployments.

Wi-Fi 6E extends Wi-Fi 6 into which additional, less congested frequency band?

• a.2.4 GHz
• b.6 GHz✓
• c.60 GHz
• d.900 MHz

Wi-Fi 6E adds the 6 GHz band, providing many new non-overlapping channels free of legacy device congestion. This reduces interference and supports wide channels for high throughput. Only 6E-capable clients can use the 6 GHz spectrum.

Which wireless standard, branded Wi-Fi 4, first introduced MIMO and can operate in both the 2.4 GHz and 5 GHz bands?

• a.802.11ac
• b.802.11a
• c.802.11n✓
• d.802.11b

802.11n, marketed as Wi-Fi 4, introduced MIMO with multiple antennas and channel bonding, and it works in both 2.4 and 5 GHz. 802.11ac (Wi-Fi 5) operates only in 5 GHz. The dual-band flexibility of 802.11n made it widely adopted.

In an enterprise wireless deployment, which device centrally manages configuration, RF, and roaming for many lightweight access points?

• a.A wireless LAN controller✓
• b.A router-on-a-stick
• c.A layer 2 switch
• d.A DHCP server

A wireless LAN controller (WLC) centrally manages lightweight access points, handling configuration, channel and power tuning, and seamless roaming. This scales far better than configuring each autonomous AP individually. The controller also enforces consistent security policy across all APs.

Which antenna type focuses radio energy in one direction to extend range on a point-to-point link between two buildings?

• a.Isotropic antenna
• b.Omnidirectional dipole
• c.Rubber duck antenna
• d.Directional (Yagi) antenna✓

A directional antenna such as a Yagi concentrates energy into a narrow beam, increasing range and gain along one axis for point-to-point links. Omnidirectional antennas radiate in all horizontal directions for general coverage. Directional antennas require careful aiming between the two endpoints.

Which technique combines adjacent channels into a wider channel, such as 40 or 80 MHz, to increase wireless throughput?

• a.Frequency hopping
• b.Band steering
• c.Channel bonding✓
• d.MAC filtering

Channel bonding merges adjacent channels into a wider one to carry more data, boosting throughput. It works best in the 5 GHz and 6 GHz bands where spectrum is plentiful. In the crowded 2.4 GHz band, wide channels cause interference and are discouraged.

Which access point feature encourages dual-band capable clients to connect on 5 GHz instead of the more crowded 2.4 GHz band?

• a.Power over Ethernet
• b.Band steering✓
• c.Beamforming
• d.Roaming

Band steering nudges capable clients onto the less congested 5 GHz band to improve performance and free up 2.4 GHz for legacy devices. It works by influencing how the AP responds to client probes. This balances load across bands automatically.

Wireless clients that all connect through a central access point rather than directly to each other are operating in which mode?

• a.Infrastructure mode✓
• b.Monitor mode
• c.Mesh backhaul mode
• d.Ad hoc mode

In infrastructure mode, clients associate with a central access point that coordinates all communication, which is the standard enterprise and home setup. Ad hoc mode connects devices peer-to-peer without an AP. Infrastructure mode scales and secures far better than ad hoc.

Which device sits between clients and the internet, forwarding requests on their behalf and often caching content and filtering URLs?

• a.A media converter
• b.A proxy server✓
• c.A DHCP relay
• d.A layer 2 switch

A proxy server forwards client requests to the internet, can cache frequently requested content, and can filter or log web activity. It centralizes control over outbound traffic. Forward proxies serve internal clients, while reverse proxies front internal servers.

Which device distributes incoming client requests across a pool of backend servers to improve capacity and availability?

• a.Hub
• b.Patch panel
• c.Repeater
• d.Load balancer✓

A load balancer spreads incoming requests across multiple backend servers using algorithms like round robin or least connections, improving scalability and resilience. If one server fails, traffic shifts to the others. It also enables maintenance without downtime.

Which device connects a copper Ethernet segment to a fiber segment by converting between electrical and optical signaling?

• a.KVM switch
• b.Punchdown block
• c.Media converter✓
• d.Loopback plug

A media converter translates between copper and fiber media, extending a link across the boundary between the two. It operates at the physical layer, converting electrical signals to light and back. It is common where fiber is needed to reach beyond copper's distance limit.

Which firewall type tracks the state of active connections and permits return traffic only for sessions it has already seen?

• a.Packet-filtering (stateless) firewall
• b.Proxy-only gateway
• c.Layer 2 transparent bridge
• d.Stateful firewall✓

A stateful firewall maintains a connection table and allows return traffic only for sessions it recognizes as established, providing stronger control than stateless filtering. Stateless firewalls evaluate each packet in isolation against static rules. Statefulness is standard in modern firewalls.