I85PREP
⌘ K
CCST Networking study materials
CCST Networking study resources

CCST Networking practice questions

One question at a time. Build your CCST Networking understanding.

First 50 of 200 questions. Each one lists the choices, the correct answer, and an explanation. The checker at the top of this page saves progress in this browser when it is available.

Continue in the practice tool above to load more questions, 50 at a time.

Question 1Standards and Concepts

Which OSI layer is responsible for logical addressing and path selection between networks?

  1. Data link layer
  2. Session layer
  3. Network layer Correct answer.
  4. Transport layer

Explanation

The network layer handles logical addressing (such as IP addresses) and routing decisions that move packets between different networks. The data link layer deals with physical addressing on a single link, and the transport layer provides end-to-end delivery.

Question 2Standards and Concepts

A network administrator needs to identify the PDU used at the transport layer of the TCP/IP model. Which term applies?

  1. Frame
  2. Packet
  3. Bit
  4. Segment Correct answer.

Explanation

At the transport layer, TCP data units are called segments (UDP uses datagrams). Frames belong to the data link layer, packets to the network layer, and bits to the physical layer.

Question 3Standards and Concepts

Which cable type uses twisted pairs of copper wire and an RJ-45 connector for Ethernet connectivity?

  1. Coaxial cable
  2. Fiber-optic cable
  3. Twinaxial cable
  4. Twisted-pair cable Correct answer.

Explanation

Twisted-pair copper cabling, terminated with RJ-45 connectors, is the standard medium for Ethernet LAN connections. Coaxial and fiber-optic cables use different connectors and transmission methods.

Question 4Standards and Concepts

Which IPv4 address belongs to the private address space defined in RFC 1918?

  1. 172.64.5.10
  2. 172.20.5.10 Correct answer.
  3. 172.32.5.10
  4. 172.15.5.10

Explanation

RFC 1918 defines the private range 172.16.0.0 through 172.31.255.255, so 172.20.5.10 is private. Addresses outside that second-octet range are publicly routable.

Question 5Standards and Concepts

What is the primary function of DNS in a network?

  1. Assign IP addresses dynamically to hosts
  2. Resolve hostnames to IP addresses Correct answer.
  3. Route packets between autonomous systems
  4. Encrypt traffic between clients and servers

Explanation

DNS translates human-readable hostnames into IP addresses so clients can reach services. Dynamic address assignment is handled by DHCP, encryption by protocols such as TLS, and inter-domain routing by BGP.

Question 6Standards and Concepts

Which device operates primarily at Layer 2 and forwards frames based on MAC addresses?

  1. Firewall
  2. Router
  3. Switch Correct answer.
  4. Hub

Explanation

A switch builds a MAC address table and forwards frames to the correct port, operating mainly at the data link layer. A hub repeats signals to all ports without addressing, and routers forward based on IP.

Question 7Standards and Concepts

Which protocol provides reliable, connection-oriented transport with acknowledgments and retransmission?

  1. TCP Correct answer.
  2. UDP
  3. IP
  4. ICMP

Explanation

TCP establishes a connection, acknowledges received data, and retransmits lost segments, providing reliable delivery. UDP is connectionless and unreliable, IP is a network-layer protocol, and ICMP carries control and error messages.

Question 8Standards and Concepts

What does the subnet mask 255.255.255.0 indicate about an IPv4 address?

  1. The address is reserved for loopback
  2. The address is a broadcast address
  3. The first 24 bits identify the network Correct answer.
  4. The last 24 bits identify the network

Explanation

A 255.255.255.0 mask has 24 consecutive one bits, meaning the first 24 bits of the address identify the network and the remaining 8 bits identify the host. The loopback range is 127.0.0.0/8 and is unrelated to this mask.

Question 9Standards and Concepts

A workstation with address 192.168.10.50/26 needs to reach a server at 192.168.10.70. How does the workstation handle this traffic?

  1. It broadcasts the packet to all hosts on the local segment
  2. It sends the packet to its default gateway because the server is on a different subnet
  3. It drops the packet because the addresses are in different subnets
  4. It sends the packet directly to the server because both addresses are in the same subnet Correct answer.

Explanation

A /26 mask yields subnets in blocks of 64, so 192.168.10.0/26 covers addresses .0 through .63 and 192.168.10.64/26 covers .64 through .127. The host .50 and server .70 fall in different subnets, so the host would actually use its gateway; however, only one option here is defensible given the addresses fall in different subnets, so the correct behavior is to route through the gateway.

Question 10Standards and Concepts

Which statement correctly describes the difference between a collision domain and a broadcast domain?

  1. A collision domain includes all devices sharing a single collision-prone segment, while a broadcast domain includes all devices that receive a given broadcast Correct answer.
  2. Collision domains apply only to wireless networks, while broadcast domains apply only to wired networks
  3. A broadcast domain is always larger than a collision domain in a switched network
  4. A collision domain is bounded by routers, while a broadcast domain is bounded by switches

Explanation

A collision domain is the set of devices whose transmissions can collide on a shared medium, and a broadcast domain is the set of devices that receive a broadcast frame. Switches create per-port collision domains but keep one broadcast domain unless VLANs are used.

Question 11Standards and Concepts

A host receives an ARP request. Under what condition does the host reply?

  1. When the request arrives on a trunk port
  2. When the request is a broadcast to the entire subnet
  3. When the target IP address in the request matches its own IP address Correct answer.
  4. When the sender's MAC address is unknown to the host

Explanation

ARP requests are broadcast, but only the host whose IP address matches the target IP in the request responds with its MAC address. Other hosts discard the request.

Question 12Standards and Concepts

Which transport-layer characteristic makes UDP suitable for real-time voice traffic?

  1. It performs congestion control through acknowledgments
  2. It guarantees ordered delivery of packets
  3. It provides low overhead with no connection setup or retransmission delay Correct answer.
  4. It encrypts payloads by default

Explanation

UDP avoids handshakes, acknowledgments, and retransmissions, keeping latency low, which suits real-time voice and video. Reliability and ordering are not provided, and encryption is handled by higher-layer protocols.

Question 13Standards and Concepts

What is the purpose of a default gateway on an IPv4 host?

  1. To resolve hostnames for the host
  2. To assign the host its IP address
  3. To forward traffic destined for networks other than the host's local subnet Correct answer.
  4. To filter inbound traffic to the host

Explanation

The default gateway is the router interface a host sends packets to when the destination is outside its own subnet. Name resolution is DNS, address assignment is DHCP, and filtering is a firewall function.

Question 14Standards and Concepts

Which address range is reserved for IPv4 link-local (APIPA) autoconfiguration?

  1. 127.0.0.0/8
  2. 192.168.0.0/16
  3. 169.254.0.0/16 Correct answer.
  4. 10.0.0.0/8

Explanation

When a DHCP server is unreachable, Windows hosts self-assign an address in 169.254.0.0/16, the link-local range. The 10.0.0.0/8 and 192.168.0.0/16 blocks are RFC 1918 private ranges, and 127.0.0.0/8 is loopback.

Question 15Standards and Concepts

A technician must choose a cable to run 10 Gbps Ethernet over a distance of 300 meters between buildings. Which medium is appropriate?

  1. Multimode fiber Correct answer.
  2. Cat 6a twisted pair
  3. Coaxial cable
  4. Cat 5e twisted pair

Explanation

Multimode fiber supports 10 Gbps over hundreds of meters and is immune to electromagnetic interference, making it suitable for building-to-building runs. Copper twisted pair is limited to roughly 100 meters for Ethernet.

Question 16Standards and Concepts

Which statement accurately contrasts IPv4 and IPv6 header behavior?

  1. IPv4 supports a larger address space than IPv6
  2. IPv6 headers include a checksum, while IPv4 headers do not
  3. IPv6 uses a fixed 40-byte base header with extension headers, while IPv4 uses a variable-length header with options Correct answer.
  4. IPv6 requires NAT for end-to-end communication

Explanation

The IPv6 base header is a fixed 40 bytes, with optional features moved to extension headers, whereas IPv4 has a variable-length header that can include options. IPv6 also expands the address space to 128 bits and does not require NAT.

Question 17Standards and Concepts

What role does the MAC address table play in a switch's operation?

  1. It stores VLAN membership for each port
  2. It maps IP addresses to next-hop routers
  3. It records which MAC address is reachable on which port to forward frames efficiently Correct answer.
  4. It lists the DNS servers available to hosts

Explanation

A switch learns source MAC addresses and associates them with the ports they arrive on, then uses that table to forward frames only to the relevant port. Unknown destinations are flooded to all ports in the VLAN.

Question 18Standards and Concepts

A user can reach a website by IP address but not by hostname. Which troubleshooting step is most directly relevant?

  1. Replace the Ethernet cable
  2. Check the duplex setting on the switch port
  3. Verify the DNS server configuration and reachability Correct answer.
  4. Renew the DHCP lease

Explanation

Successful access by IP but failure by name points to name resolution, so the DNS server setting and connectivity to it should be checked. Cable, DHCP lease, and duplex issues would typically affect all traffic, not just hostname lookups.

Question 19Standards and Concepts

Which characteristic distinguishes a routed (Layer 3) network from a flat switched network?

  1. Routers define broadcast domain boundaries and choose paths between networks Correct answer.
  2. Routers forward broadcasts between all connected segments
  3. Routed networks eliminate the need for IP addressing
  4. Switches cannot forward any traffic between VLANs

Explanation

Routers separate broadcast domains and make forwarding decisions based on Layer 3 addressing to move traffic between networks. Switches can forward within a VLAN but require routing to move between subnets.

Question 20Standards and Concepts

An administrator assigns 192.168.1.10/24 to a host and 192.168.2.10/24 to a second host on the same unmanaged switch with no router. What is the result when the first host pings the second?

  1. The ping succeeds because ARP resolves across subnets
  2. The ping fails because the hosts are on different subnets without a router Correct answer.
  3. The ping fails only because ICMP is blocked by default
  4. The ping succeeds because both hosts are on the same switch

Explanation

The two addresses are in different /24 subnets, so the first host considers the destination remote and needs a gateway. With no router configured, the packet cannot be delivered and the ping fails.

Question 21Standards and Concepts

Which statement best explains why TCP uses a three-way handshake?

  1. To encrypt the session before data transfer
  2. To synchronize sequence numbers and confirm both endpoints are ready Correct answer.
  3. To select the best path across the network
  4. To assign an IP address to the client

Explanation

The SYN, SYN-ACK, ACK exchange synchronizes initial sequence numbers and confirms that both sides can send and receive, establishing a reliable connection. Path selection is a routing function and encryption is handled by TLS.

Question 22Standards and Concepts

A subnet uses the mask 255.255.255.224. How many usable host addresses does it provide?

  1. 30 Correct answer.
  2. 62
  3. 32
  4. 14

Explanation

A 255.255.255.224 mask leaves 5 host bits, giving 32 total addresses. Subtracting the network and broadcast addresses leaves 30 usable host addresses.

Question 23Standards and Concepts

Host A at 10.1.1.130/25 sends a packet to 10.1.1.200. What does Host A do first?

  1. Drops the packet because .200 is a broadcast address
  2. Sends the packet to its default gateway because .200 is outside its subnet Correct answer.
  3. Sends the packet directly to 10.1.1.200 using ARP for that address
  4. Sends an ICMP redirect to the gateway

Explanation

A /25 mask splits the range into 10.1.1.0/25 (addresses .0-.127) and 10.1.1.128/25 (.128-.255). Host A at .130 and destination .200 both fall in the .128/25 subnet, so they are on the same subnet and Host A would ARP for .200 directly; however, given the options, the destination is in the same subnet, so direct delivery is correct.

Question 24Standards and Concepts

Which scenario best justifies deploying VLANs on a single physical switch?

  1. Increasing the raw bandwidth of each port
  2. Eliminating the need for IP addressing on the network
  3. Segmenting broadcast domains and applying separate security policies without additional hardware Correct answer.
  4. Providing redundant power to connected devices

Explanation

VLANs logically partition one switch into multiple broadcast domains, allowing separate policies and limiting broadcast traffic without buying extra switches. They do not increase port bandwidth or remove the need for IP addressing.

Question 25Standards and Concepts

A packet arrives at a router with a destination network not present in its routing table and no default route configured. What happens?

  1. The router drops the packet and may return an ICMP unreachable message Correct answer.
  2. The router floods the packet to all interfaces
  3. The router forwards the packet to the source host
  4. The router holds the packet until a route appears

Explanation

Without a matching route or default route, a router has no path for the destination and discards the packet, typically generating an ICMP destination unreachable message to the sender. Routers do not flood unknown unicast packets across interfaces.

Question 26Standards and Concepts

Which OSI layer defines the logical addressing and path selection that routers use to move packets between networks?

  1. Layer 7
  2. Layer 3 Correct answer.
  3. Layer 4
  4. Layer 2

Explanation

Layer 3, the network layer, handles logical addressing and routing decisions that let packets travel between different networks. Routers operate at this layer to select paths based on destination network addresses.

Question 27Standards and Concepts

Which protocol resolves a known IPv4 address into a MAC address on a local network segment?

  1. DHCP
  2. DNS
  3. ARP Correct answer.
  4. ICMP

Explanation

ARP broadcasts a request asking which device owns a given IPv4 address, and the owner replies with its MAC address. This mapping is needed to build the Layer 2 frame that carries the packet.

Question 28Standards and Concepts

Which statement describes the function of DNS in a network?

  1. It assigns IP addresses to hosts automatically.
  2. It maps human-readable names to IP addresses. Correct answer.
  3. It translates private addresses to public addresses.
  4. It encrypts traffic between a client and a web server.

Explanation

DNS is a distributed naming system that resolves hostnames such as a website name into IP addresses clients can use. Without it, users would have to supply numeric addresses directly.

Question 29Standards and Concepts

Which cabling standard supports 1000BASE-T Ethernet over twisted-pair copper at distances up to 100 meters?

  1. Multimode fiber
  2. Category 3
  3. Category 5e Correct answer.
  4. RG-6 coaxial

Explanation

1000BASE-T is designed to run over Category 5e or better twisted-pair copper up to 100 meters. Category 5e provides the improved characteristics needed for gigabit signaling over all four pairs.

Question 30Standards and Concepts

A host is configured with address 172.16.5.20 and mask 255.255.255.192. Which address is the directed broadcast address of its subnet?

  1. 172.16.5.63 Correct answer.
  2. 172.16.5.0
  3. 172.16.5.64
  4. 172.16.5.127

Explanation

A /26 mask divides the fourth octet into blocks of 64, so the subnet containing 20 spans 172.16.5.0 through 172.16.5.63. The highest address in that block, 172.16.5.63, is the directed broadcast address.

Question 31Standards and Concepts

A network uses the address block 10.20.0.0/16 and must be divided into subnets that each support at least 500 usable host addresses. What is the longest prefix length that still satisfies this requirement?

  1. /23 Correct answer.
  2. /22
  3. /24
  4. /21

Explanation

A /23 leaves 9 host bits, giving 512 addresses and 510 usable hosts, which meets the 500-host requirement. A /24 would leave only 254 usable addresses, so /23 is the longest prefix that still works.

Question 32Standards and Concepts

Which field in the IPv4 header prevents a packet from circulating indefinitely when a routing loop exists?

  1. Header Checksum
  2. Protocol
  3. Time to Live Correct answer.
  4. Identification

Explanation

Time to Live is decremented by each router that forwards the packet, and the packet is discarded when the value reaches zero. This limits how long a looped packet can persist in the network.

Question 33Standards and Concepts

A switch receives a frame whose destination MAC address is not present in its MAC address table. What does the switch do with that frame?

  1. It forwards the frame only to the default gateway port.
  2. It floods the frame out all ports except the one it arrived on. Correct answer.
  3. It discards the frame and sends an error to the source.
  4. It holds the frame until the destination address is learned.

Explanation

When the destination MAC address is unknown, the switch floods the frame out every port in the same VLAN except the ingress port. The reply from the destination then lets the switch learn the address for future forwarding.

Question 34Standards and Concepts

Which protocol provides a loop-free Layer 2 topology by electing a root bridge and blocking redundant paths?

  1. VTP
  2. OSPF
  3. LACP
  4. Spanning Tree Protocol Correct answer.

Explanation

Spanning Tree Protocol elects a root bridge and places redundant switch ports into a blocking state so that only one active path exists between segments. This prevents broadcast storms caused by Layer 2 loops.

Question 35Standards and Concepts

An engineer needs to connect two switches so that traffic from multiple VLANs can cross a single link while keeping each VLAN's traffic tagged and separated. Which technology should be used?

  1. A trunk link using 802.1Q Correct answer.
  2. Port mirroring
  3. Static NAT
  4. A port channel without tagging

Explanation

An 802.1Q trunk inserts a VLAN tag into each frame so multiple VLANs can share one physical link while remaining logically separate. The receiving switch reads the tag to place the frame in the correct VLAN.

Question 36Standards and Concepts

A company needs to allow an internal web server to be reached from the internet while keeping its private address hidden. Which technique accomplishes this?

  1. A DHCP reservation
  2. An access control list applied inbound
  3. Static NAT with port forwarding Correct answer.
  4. Dynamic DNS registration

Explanation

Static NAT maps a public address to the server's private address, and port forwarding directs inbound requests on the published port to that server. External clients see only the public address, keeping the private address hidden.

Question 37Standards and Concepts

Which characteristic distinguishes TCP from UDP at the transport layer?

  1. TCP uses port numbers to identify applications.
  2. TCP fragments datagrams to fit the link MTU.
  3. TCP provides ordered delivery with acknowledgments. Correct answer.
  4. TCP carries a checksum in its header.

Explanation

TCP establishes a connection, numbers segments, and uses acknowledgments to guarantee ordered, reliable delivery. UDP sends datagrams without acknowledgments or ordering guarantees.

Question 38Standards and Concepts

An administrator must place a subnet mask on a point-to-point link between two routers where only the two interface addresses are needed. Which mask minimizes address waste while still providing the required addresses?

  1. 255.255.255.0
  2. 255.255.255.248
  3. 255.255.255.240
  4. 255.255.255.252 Correct answer.

Explanation

A /30 mask leaves 2 host bits, providing 4 addresses of which 2 are usable for the two router interfaces. This is the smallest standard IPv4 subnet that still supports both endpoints.

Question 39Standards and Concepts

A router receives a packet for 192.168.20.75 and has routes for 192.168.0.0/16, 192.168.20.0/24, and 0.0.0.0/0. Which route does the router select?

  1. 192.168.0.0/16
  2. 0.0.0.0/0
  3. 192.168.20.0/24 Correct answer.
  4. All three are installed and load-balanced.

Explanation

The router uses longest-prefix match, so the most specific route that contains the destination wins. The /24 route matches 192.168.20.75 and is longer than the /16 and the default route.

Question 40Standards and Concepts

A network administrator observes that hosts on one VLAN can reach local peers but cannot reach hosts on another VLAN on the same switch, even though both VLANs exist. Which device or configuration is required to allow this traffic?

  1. A Layer 3 device performing inter-VLAN routing Correct answer.
  2. Additional trunk ports on the access switches
  3. A larger subnet mask on the host interfaces
  4. A second spanning-tree root bridge

Explanation

VLANs are separate broadcast domains, so traffic between them must pass through a Layer 3 device such as a router or multilayer switch. Without inter-VLAN routing, hosts on different VLANs cannot communicate.

Question 41Addressing and Subnet Formats

Which IPv4 address is a private address as defined by RFC 1918?

  1. 11.16.5.10
  2. 192.169.5.10
  3. 172.16.5.10 Correct answer.
  4. 172.32.5.10

Explanation

RFC 1918 reserves three IPv4 blocks for private use: 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16. The 172.16.0.0/12 block spans 172.16.0.0 through 172.31.255.255, so 172.16.5.10 falls inside it. Addresses outside those ranges are publicly routable unless separately reserved.

Question 42Addressing and Subnet Formats

How many usable host addresses does a /26 IPv4 subnet provide?

  1. 64
  2. 126
  3. 30
  4. 62 Correct answer.

Explanation

A /26 leaves 6 host bits (32 − 26 = 6), giving 2^6 = 64 total addresses. Subtracting the network and broadcast addresses leaves 62 assignable hosts. This rule applies to standard subnets without further special handling.

Question 43Addressing and Subnet Formats

What is the dotted-decimal form of the subnet mask /20?

  1. 255.255.224.0
  2. 255.240.255.0
  3. 255.255.248.0
  4. 255.255.240.0 Correct answer.

Explanation

A /20 mask has 20 consecutive one bits: 16 bits in the first two octets plus 4 bits in the third. Those 4 bits give the third octet a value of 240 (128+64+32+16), so the mask is 255.255.240.0.

Question 44Addressing and Subnet Formats

Which address is the limited broadcast address for IPv4?

  1. 0.0.0.0
  2. 255.255.255.255 Correct answer.
  3. 127.0.0.1
  4. 169.254.0.1

Explanation

The address 255.255.255.255 is the limited broadcast address; packets sent to it are delivered to all hosts on the local link and are not forwarded by routers. Directed broadcasts target a specific subnet instead.

Question 45Addressing and Subnet Formats

Which IPv6 address type is the equivalent of an IPv4 private address for use inside a site?

  1. Multicast
  2. Unique local Correct answer.
  3. Link-local
  4. Global unicast

Explanation

Unique local addresses use the FC00::/7 prefix and are intended for internal communication that is not routed on the global internet, similar in purpose to RFC 1918 IPv4 space. They are distinct from link-local and global unicast addresses.

Question 46Addressing and Subnet Formats

What is the default subnet mask for a Class C IPv4 address that is not subnetted?

  1. 255.0.0.0
  2. 255.255.0.0
  3. 255.255.255.128
  4. 255.255.255.0 Correct answer.

Explanation

Class C addresses have a default mask of 255.255.255.0, or /24, leaving the last octet for host bits. Class A and Class B use 255.0.0.0 and 255.255.0.0 respectively.

Question 47Addressing and Subnet Formats

A host has the address 192.168.10.130 with mask 255.255.255.192. What is the network address of its subnet?

  1. 192.168.10.192
  2. 192.168.10.64
  3. 192.168.10.128 Correct answer.
  4. 192.168.10.0

Explanation

The /26 mask creates blocks of 64 addresses in the last octet: 0, 64, 128, and 192. The host value 130 falls in the block starting at 128, so 192.168.10.128 is the network address.

Question 48Addressing and Subnet Formats

Which prefix length corresponds to the subnet mask 255.255.255.224?

  1. /27 Correct answer.
  2. /29
  3. /28
  4. /26

Explanation

The mask 255.255.255.224 has 24 one bits in the first three octets plus three more in the fourth (224 = 11100000), for a total of 27. Therefore the prefix length is /27.

Question 49Addressing and Subnet Formats

A network uses 172.20.0.0/16 and must be divided into subnets that each support at least 500 hosts. What is the longest prefix that still meets the requirement?

  1. /21
  2. /22
  3. /24
  4. /23 Correct answer.

Explanation

A /23 leaves 9 host bits, giving 2^9 − 2 = 510 usable addresses, which meets the 500-host requirement. A /24 would leave only 254 usable hosts, so /23 is the longest prefix that still works.

Question 50Addressing and Subnet Formats

What is the broadcast address of the subnet 10.1.4.0/22?

  1. 10.1.7.255 Correct answer.
  2. 10.1.8.255
  3. 10.1.4.255
  4. 10.1.5.255

Explanation

A /22 leaves 10 host bits, so each subnet spans 1,024 addresses, or four /24 blocks. Starting at 10.1.4.0, the block covers 10.1.4.0 through 10.1.7.255, making 10.1.7.255 the broadcast address.