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22 Networking, Virtualization & Cloud Practice Questions & Answers

Every Networking, Virtualization & Cloud practice question from the CompTIA A+ Practice Test, with the correct answer and a short explanation.

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  1. 1. A technician must administer a Linux server's command line from across the building, and policy forbids sending passwords in cleartext. Which port should be opened on the server firewall?

    • A.TCP 22, carrying the encrypted SSH remote shell session✓ Answer
    • B.UDP 69, carrying the TFTP download used for device images
    • C.TCP 23, carrying the Telnet remote shell session in cleartext
    • D.TCP 25, carrying SMTP message transfer between mail servers

    SSH listens on TCP 22 and encrypts the whole terminal session, including the login, which is exactly what the policy requires. Telnet on TCP 23 is the tempting pick because it does the same job of giving a remote command line, but it sends the user name, password and every keystroke as readable text on the wire.

    Source: CompTIA A+ Core 1 exam objectives, TCP and UDP ports and protocols list (SSH and Telnet)Report a problem with this question

  2. 2. An internal web application asks users for a name and password on a page delivered over plain HTTP. What should the technician change to protect those credentials in transit?

    • A.Move the application to TCP 8080 so the traffic bypasses the content proxy
    • B.Leave the application on HTTP over TCP 80 and enforce longer user passwords
    • C.Publish the application over HTTPS on TCP 443 so the session is encrypted✓ Answer
    • D.Offer the application over FTP on TCP 21 so the browser prompts for a login

    HTTPS on TCP 443 wraps the same web traffic in TLS, so the posted name and password cannot be read off the wire. Longer passwords feel like a security improvement, but a password of any length still crosses the network in readable form when the page is served over HTTP on port 80.

    Source: CompTIA A+ Core 1 exam objectives, TCP and UDP ports and protocols list (HTTP and HTTPS)Report a problem with this question

  3. 3. A help desk technician needs to take control of the graphical desktop of a Windows workstation on the same LAN. Which port must the workstation's firewall allow?

    • A.TCP 143, where a mail client reaches its IMAP folders
    • B.TCP 389, where directory queries to LDAP are answered
    • C.TCP 3389, where a Remote Desktop session is accepted✓ Answer
    • D.TCP 445, where Windows file and printer sharing runs

    Remote Desktop Protocol listens on TCP 3389, so that port must be reachable before the technician can drive the remote screen, keyboard and mouse. TCP 445 tempts because it is the other well known Windows port a technician opens every day, but it carries SMB file and printer sharing and gives no view of the desktop.

    Source: CompTIA A+ Core 1 exam objectives, TCP and UDP ports and protocols list (RDP and SMB)Report a problem with this question

  4. 4. A vendor uploads nightly files to a company server with FTP. A packet capture shows the vendor's password in readable text. Which change removes that exposure?

    • A.Switch the transfer to SFTP, which carries the whole session inside SSH on port 22✓ Answer
    • B.Keep FTP on port 21 and set the client to passive mode for the data channel
    • C.Keep FTP on port 21 and rotate the vendor account password every thirty days
    • D.Switch the transfer to TFTP, which uses UDP port 69 and asks for no login

    SFTP runs the whole file transfer, credentials included, inside an SSH session on TCP 22, so a capture shows only ciphertext. Passive mode is the tempting answer because technicians change it so often to get FTP working through a firewall, but it only decides which side opens the data connection and leaves the login in cleartext.

    Source: CompTIA A+ Core 1 exam objectives, TCP and UDP ports and protocols list (FTP and SSH)Report a problem with this question

  5. 5. A user reads company mail on a phone, a tablet and a laptop, and wants a message marked read on one device to appear read on the others. Which mail protocol should be configured?

    • A.IMAP on port 143, which keeps the messages on the server for every client✓ Answer
    • B.LDAP on port 389, which looks up the user's mail attributes in the directory
    • C.POP3 on port 110, which downloads the messages and clears them off the server
    • D.SMTP on port 25, which hands outgoing messages from one mail server to another

    IMAP on TCP 143 leaves the mailbox on the server and synchronizes folder and read state to every client, so all three devices show the same view. POP3 on TCP 110 is the classic wrong pick here because it also retrieves mail, but its default behavior downloads each message to one device and deletes the server copy.

    Source: CompTIA A+ Core 1 exam objectives, TCP and UDP ports and protocols list (POP3 and IMAP)Report a problem with this question

  6. 6. A supervisor asks why the company's voice and video calls are carried over UDP instead of TCP. What is the correct explanation?

    • A.The payload is compressed in transit, so a call uses far less bandwidth
    • B.A lost packet is resent immediately, so no audio sample is ever missing
    • C.The delivery order is guaranteed, so voice frames always play in sequence
    • D.A lost packet is simply discarded, so no retransmission delays the live audio✓ Answer

    Real-time media values timeliness over completeness: UDP does not acknowledge or resend, so one dropped packet becomes a brief glitch rather than a pause while the sender waits and retransmits. The idea that UDP resends quickly is the common confusion, but acknowledgment and retransmission are TCP behaviors, and they are what makes TCP a poor fit for live calls.

    Source: CompTIA A+ Core 1 exam objectives, comparison of TCP and UDP transport characteristicsReport a problem with this question

  7. 7. A desktop that normally gets its address automatically now shows 169.254.18.7 with a mask of 255.255.0.0 and no default gateway, and it reaches nothing on the network. What does this indicate?

    • A.A rogue DHCP server on another subnet answered and issued this lease
    • B.The network adapter is failing and reports an invented address to Windows
    • C.A previous technician left a static public address in the adapter settings
    • D.No DHCP server answered, so the client gave itself a link-local address✓ Answer

    Anything in 169.254.x.x with no gateway is an automatic private address the host assigns to itself after its DHCP requests go unanswered, which is why the machine can talk to nobody beyond its own link. A rogue DHCP server is a real problem technicians meet, but a rogue server hands out a usable address and gateway of its own; the missing gateway here shows no server replied at all.

    Source: CompTIA A+ Core 1 exam objectives, IP addressing section covering APIPA and link-local addressesReport a problem with this question

  8. 8. Which of these IPv4 addresses comes from a range reserved for private use inside an organization?

    • A.172.35.4.15, which falls inside the 172.32.0.0/12 private block
    • B.11.10.4.15, which falls inside the 11.0.0.0/8 private block
    • C.172.20.4.15, which falls inside the 172.16.0.0/12 private block✓ Answer
    • D.192.169.4.15, which falls inside the 192.169.0.0/16 private block

    The three private ranges are 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16, and 172.20.4.15 sits in the middle block, which spans 172.16 through 172.31. The 172.35 answer is the trap because the second octet looks similar, but the private range stops at 172.31, so 172.32 and above are public addresses assigned to other organizations.

    Source: CompTIA A+ Core 1 exam objectives, private versus public IPv4 address rangesReport a problem with this question

  9. 9. A workstation is set to 192.168.1.40 with mask 255.255.255.0 and gateway 192.168.10.1. It prints to the LAN printer and opens the file server, but no website loads, even when typed as a numeric address. What is the cause?

    • A.The gateway address is outside the local subnet, so no router receives the traffic✓ Answer
    • B.The DNS server entry is blank, so the browser cannot look up any site names
    • C.The subnet mask is far too wide, so the host treats every destination as local
    • D.The patch cable is damaged, so only frames below the local segment size pass

    With a /24 mask the host can only hand off-subnet traffic to a router inside 192.168.1.x, and 192.168.10.1 is not on that subnet, so anything destined off the LAN is never forwarded while local hosts still work. A blank DNS entry is the usual suspect for this symptom, but the stem rules it out: typing a numeric address needs no name lookup and still fails.

    Source: CompTIA A+ Core 1 exam objectives, SOHO network configuration covering subnet mask and default gatewayReport a problem with this question

  10. 10. Which line shows the address 2001:0db8:0000:0000:0000:ff00:0042:8329 correctly written in its shortened form?

    • A.2001.0db8.0.0.0.ff00.42.8329, with dots separating the eight address groups
    • B.2001:db8::ff00:42:8329, with the single run of zero groups replaced once✓ Answer
    • C.2001:0db8:ff00:42:8329, with the three zero groups deleted from the address
    • D.2001:db8::0::ff00:42:8329, with a double colon marking each zero group kept

    An IPv6 address is eight groups of four hex digits; leading zeros in a group may be dropped and one run of all-zero groups may be replaced by a double colon, which yields 2001:db8::ff00:42:8329. Using a double colon twice is the tempting shortcut, but it is invalid because a reader could no longer tell how many zero groups belong to each gap.

    Source: CompTIA A+ Core 1 exam objectives, IPv6 addressing in the network configuration sectionReport a problem with this question

  11. 11. Mail sent to a company's domain bounces back to outside senders. Which DNS record type tells a sending server which host accepts mail for that domain?

    • A.The A record, which maps a host name to its IPv4 address for clients
    • B.The CNAME record, which points one host name at another as an alias
    • C.The AAAA record, which maps a host name to its IPv6 address for clients
    • D.The MX record, which names the host that receives mail for the domain✓ Answer

    Mail exchanger records are what a sending server queries to find the host, and the priority order of hosts, that accepts mail for a domain, so a missing or wrong MX record makes delivery bounce. The A record is tempting because the mail host does need one to resolve to an address, but a correct A record alone never advertises that the host handles mail.

    Source: CompTIA A+ Core 1 exam objectives, DNS record types including A, AAAA, CNAME and MXReport a problem with this question

  12. 12. A company must publish a policy that lists which servers are allowed to send mail using its domain name. Which DNS record type carries that policy?

    • A.The MX record, which holds the priority of each inbound mail host
    • B.The TXT record, which holds the SPF, DKIM and DMARC policy text strings✓ Answer
    • C.The PTR record, which holds the reverse lookup from address to name
    • D.The CNAME record, which holds an alias from one host name to another

    Sender policy statements are published as text strings in TXT records, which is how SPF lists the permitted sending hosts and how DKIM and DMARC publish their keys and handling rules. MX is the tempting answer because the subject is mail, but MX records only advertise where inbound mail should be delivered and say nothing about who may send as the domain.

    Source: CompTIA A+ Core 1 exam objectives, DNS TXT records used for spam management with SPF, DKIM and DMARCReport a problem with this question

  13. 13. A networked printer keeps changing its address, which breaks the print queues on client PCs. The technician wants to fix its address centrally from the DHCP server without touching the printer's panel. What should be configured?

    • A.A reservation binding the printer's MAC address to one address in the scope✓ Answer
    • B.A shorter lease time so the printer renews the same address more frequently
    • C.A wider scope so spare addresses are always left available for the printer
    • D.An exclusion removing the printer's current address from the assignable scope

    A reservation ties a specific hardware address to a specific IP inside the scope, so the printer keeps asking by DHCP as usual and always receives the same address, all managed from the server. An exclusion is the tempting neighbor because it also involves a specific address, but it only stops the server from handing that address to anyone, which would leave the printer with a different one.

    Source: CompTIA A+ Core 1 exam objectives, DHCP leases, reservations, scope and exclusionsReport a problem with this question

  14. 14. A busy office segment is slow, so the technician replaces its hub with a switch. Why does that reduce collisions and raise throughput?

    • A.The switch repeats each frame out every port, but at a much faster clock rate
    • B.The switch sends each frame only out the port where its destination MAC sits✓ Answer
    • C.The switch discards all broadcast frames, leaving only unicast traffic on the wire
    • D.The switch gives each host a public address so the hosts no longer share a subnet

    A switch learns which MAC address lives behind each port and forwards a frame only there, so every port becomes its own collision domain instead of one shared segment. Believing the switch is simply a faster hub is the common misconception, but repeating every frame out every port is exactly the hub behavior that creates the collisions in the first place.

    Source: CompTIA A+ Core 1 exam objectives, common networking hardware devices including switches and hubsReport a problem with this question

  15. 15. A laptop two interior walls away from the access point holds a steady connection on the 2.4 GHz network but keeps dropping the 5 GHz one. What explains the difference?

    • A.Higher frequencies pass through walls better, but 5 GHz channels are more crowded
    • B.The 2.4 GHz band has only three non-overlapping channels, which extends its reach
    • C.The 5 GHz radio draws more client power, so the laptop drops it to save battery
    • D.Lower frequencies pass through walls better, while 5 GHz trades range for speed✓ Answer

    Lower frequency signals lose less energy passing through drywall and studs, so 2.4 GHz reaches farther indoors while 5 GHz offers wider channels and higher throughput over a shorter, more line-of-sight distance. Channel crowding is a real 2.4 GHz weakness, but crowding does not change how far a signal penetrates, and it is the 2.4 GHz band, not 5 GHz, that has only three non-overlapping channels.

    Source: CompTIA A+ Core 1 exam objectives, wireless networking frequencies, bands and channel characteristicsReport a problem with this question

  16. 16. A 250 meter link must cross a factory floor that runs beside large motors and welding equipment. Which cable should the technician specify?

    • A.Unshielded Cat 6a, because its tighter twist rate cancels out the outside noise
    • B.Multimode fiber, because light inside glass is immune to electromagnetic noise✓ Answer
    • C.RG-6 coaxial, because the braided shield drains the interference to the chassis
    • D.Shielded Cat 5e, because the foil lets a copper run reach well beyond 100 meters

    Fiber carries the signal as light in glass, so it neither picks up electrical noise nor is limited by the 100 meter copper distance rule, which settles both problems in this run at once. Shielded twisted pair is the tempting answer because shielding does help near motors, but shielding does not extend the 100 meter limit, so a 250 meter copper run still fails.

    Source: CompTIA A+ Core 1 exam objectives, copper and optical cable types and their purposesReport a problem with this question

  17. 17. A server is built by installing virtualization software straight onto bare hardware, with no general purpose operating system underneath it. What is that software?

    • A.A Type 2 hypervisor, running as a program on top of an installed desktop OS
    • B.A virtual desktop client, streaming a remote session from a server in a farm
    • C.A container engine, packaging each application with its own separate kernel
    • D.A Type 1 hypervisor, running on the hardware and hosting the guests itself✓ Answer

    A bare-metal, or Type 1, hypervisor is itself the layer that talks to the hardware and schedules the guest machines, which is why it is used on production servers where the extra host OS would only add overhead. A Type 2 hypervisor does the same virtualization work, but it is an application installed on an existing desktop operating system, which is the detail the stem rules out.

    Source: CompTIA A+ Core 1 exam objectives, hypervisor types in the virtualization sectionReport a problem with this question

  18. 18. A developer needs dozens of isolated copies of one Linux web application on a single server, each starting in seconds with very little memory overhead. Which approach fits best?

    • A.Full virtual machines, since each boots a guest OS that isolates its own kernel
    • B.A Type 1 hypervisor, since bare-metal virtualization removes the host OS layer
    • C.Containers, since they share the host kernel instead of booting a guest OS✓ Answer
    • D.Virtual desktop infrastructure, since sessions stream from a central server pool

    Containers isolate the application and its libraries while sharing the running host kernel, so each instance starts almost immediately and costs a fraction of the memory a full guest operating system needs. Full virtual machines are the tempting choice because they isolate more thoroughly, but every one of them boots and holds its own operating system, which is precisely the overhead the developer wants to avoid.

    Source: CompTIA A+ Core 1 exam objectives, virtual machine requirements and container conceptsReport a problem with this question

  19. 19. A company rents virtual machines from a cloud provider and installs its own server operating system images on them. Who applies the operating system security patches inside those machines?

    • A.The customer, but only for the hypervisor, since tenants control the host layer
    • B.The customer, because this model delivers the virtual hardware and nothing above it✓ Answer
    • C.The provider, because this model includes the operating system as part of the rent
    • D.The provider, because every cloud model is sold as a fully managed service

    Renting virtual machines is infrastructure as a service, where the provider supplies compute, storage and network and the tenant owns everything from the guest operating system upward, patching included. Assuming the provider patches is tempting because that is true in platform and software as a service, where the vendor maintains the runtime or the whole application, but it does not hold once the customer supplies its own OS image.

    Source: CompTIA A+ Core 1 exam objectives, cloud service models IaaS, PaaS and SaaSReport a problem with this question

  20. 20. Several regional hospitals jointly fund and share one cloud platform built to meet the health privacy rules they all follow, and no outside customers use it. Which deployment model is this?

    • A.A private cloud, built and operated for the exclusive use of a single company
    • B.A community cloud, shared by organizations that carry the same requirements✓ Answer
    • C.A hybrid cloud, joining a private platform to a public one for extra capacity
    • D.A public cloud, sold from shared pools to any customer that opens an account

    A community cloud is pooled infrastructure shared by a defined set of organizations with common compliance, mission or policy needs, which is exactly the arrangement several hospitals under the same privacy rules would build. A private cloud is the tempting answer since the platform is closed to outsiders, but private means one organization owns the environment, and here the cost and control are shared among peers.

    Source: CompTIA A+ Core 1 exam objectives, cloud deployment models public, private, hybrid and communityReport a problem with this question

  21. 21. A retailer's cloud site automatically adds web servers during a holiday sales rush and releases them again when traffic falls back. Which cloud characteristic is this?

    • A.High availability, staying in service when one component of the site fails
    • B.File synchronization, mirroring stored data between devices and the cloud
    • C.Elasticity, adding and then releasing resources as the workload rises and falls✓ Answer
    • D.Multitenancy, hosting many separate customers on one shared platform

    Elasticity is the ability to scale capacity up and back down on demand, which is what lets a metered cloud bill follow actual usage instead of a year-round peak build. High availability sounds close because both promise a site that keeps working, but availability is about surviving a failed component, not about matching capacity to a changing workload.

    Source: CompTIA A+ Core 1 exam objectives, cloud characteristics including elasticity, scalability and availabilityReport a problem with this question

  22. 22. Uploading a large archive to cloud storage cost nothing, but the monthly bill jumped sharply after the company downloaded that whole archive back to its own site. What drove the charge?

    • A.Egress metering, which bills for the data that leaves the provider's network✓ Answer
    • B.Ingress metering, which bills the data that is written into the storage
    • C.Multitenant licensing, which bills each customer sharing the platform
    • D.Capacity reservation, which bills the space promised for the coming year

    Metered cloud utilization is asymmetric: providers commonly accept incoming data at no charge and bill on egress, the traffic leaving their network, so a full restore to on-premises equipment lands as a large one-time transfer cost. Blaming ingress is the natural mirror-image guess, but the stem states the upload was free, which is exactly the side that is normally not metered.

    Source: CompTIA A+ Core 1 exam objectives, cloud metered utilization including ingress and egressReport a problem with this question

Practice questions written to the published CompTIA A+ Core 1 and Core 2 exam objectives and to standard IT support practice. CompTIA and A+ are marks of CompTIA; this site is not affiliated with or endorsed by CompTIA. The exam objectives are revised periodically — confirm the current objectives and exam requirements with CompTIA before testing. About the CompTIA A+ certification →