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31 multiple-choice questions and 36 flashcards on Networking Concepts, about 11% of the CompTIA Network+ bank. Every one carries a written rationale.
Networking Concepts is one of 7 chapters in CoStudy's CompTIA Network+ bank, and it holds 31 of the bank's 270 multiple-choice questions — roughly 11% of the total. That proportion is not arbitrary: chapters follow the certifying body's published exam outline, and the number of questions in each is set by that domain's published weight, so the share of your practice time this chapter takes matches the share of the real exam it accounts for.
Studying by chapter is worth doing once you have a diagnostic score. A single overall percentage tells you whether you are close; it does not tell you which domain is dragging. Working a weak chapter in isolation, and re-testing it in isolation, is the fastest way to move a score that has stalled — and it is why the mock exams in CoStudy report by domain rather than as one number.
10 questions drawn from this chapter, with the full rationale shown — the controlling principle behind the right answer, and why each wrong option tempts and fails.
Instances in a private cloud subnet must download vendor patches from the internet, but nothing on the internet may initiate a session to them. Which configuration MOST appropriately meets both requirements?
Answer: A — Route the subnet's default path to a NAT gateway in a public subnet
A) Correct — a NAT gateway lets outbound sessions leave and return while providing no inbound reachability, which is exactly the asymmetry requested. B) An internet gateway route plus public addressing makes the instances directly addressable, which the requirement forbids. C) Public addresses with a restrictive security group is half right: it can block inbound traffic, but it still exposes routable addresses and depends entirely on rule correctness. D) Peering solves private reachability to one partner network, not general patch downloads from vendor sites.
Which is true about Layer 7 (NGFW/load balancer) versus Layer 4 load balancing?
Answer: A — L7 inspects HTTP headers, URLs, and cookies; L4 uses IP and port
A is right: a Layer 7 device sees application data such as the URL, Host header, and cookies, while a Layer 4 device forwards on the IP/port 5-tuple. B is the direction-reversed version and the classic misconception. C ignores that the two operate on different layers of the stack, not just at different speeds. D is false — modern L7 load balancers and NGFWs routinely terminate TLS.
A video service sends one stream that only subscribed receivers on the campus should receive, and the network should replicate it only where subscribers exist. Which traffic type BEST describes this?
Answer: D — Multicast, since group membership determines who receives the flow
D) Correct — multicast sends a single flow to a group address, and the network replicates it only toward segments where receivers have joined the group. A) Broadcast floods the whole segment regardless of interest and does not cross routers, wasting capacity. B) Anycast advertises one address from multiple locations for nearest-instance selection; it does not replicate a stream to many receivers. C) Unicast would create a separate copy per receiver, defeating the goal of sending one stream.
Quality of Service (QoS) is used to:
Answer: B — Prioritize latency-sensitive traffic such as VoIP over bulk file transfers
B is right: QoS classifies and marks traffic (DSCP), then applies queueing, shaping, and policing so delay-sensitive flows get bandwidth and low jitter. A is too narrow, since QoS covers voice, video, and control traffic alike. C describes firewall or ACL work. D inverts the goal, because QoS allocates bandwidth rather than removing it.
The PDU at the Transport layer for TCP is called a:
Answer: D — Segment
TCP PDU = segment. UDP PDU = datagram. Network layer PDU = packet. Data link PDU = frame. Confusing segment/datagram between TCP/UDP is a frequent question.
A retailer runs 140 stores, each with a broadband circuit and an LTE backup. Leadership wants centralized policy, application-aware path selection, and lower circuit cost than its current private WAN. Which approach BEST fits?
Answer: A — Deploy SD-WAN edge devices managed from a central controller
A) Correct — SD-WAN is the objective-named answer for geographically distributed sites: a central controller pushes policy and the edge steers traffic per application across whichever transport performs best. B) MPLS gives predictable transport but is the cost problem being solved and lacks application-aware steering. C) Static full-mesh IPsec achieves connectivity but not central policy or dynamic path selection, and it scales poorly at 140 sites. D) Load balancers distribute server or session load; they do not select WAN paths by application quality.
Which is the default port for DNS queries?
Answer: B — Port 53, using UDP for queries and TCP for zone transfers
B is right: DNS uses port 53, normally UDP for ordinary queries and TCP for zone transfers or responses too large for a single datagram. A is SSH, C is HTTP, D is SMTP, and E is HTTPS, all common ports that crowd the same memorization list. Also know 20/21 FTP, 23 Telnet, and 3389 RDP.
Which OSI layer is responsible for routing packets between networks?
Answer: B — Layer 3 (Network)
Layer 3 (Network) handles logical addressing (IP) and routing decisions between networks. Layer 2 handles framing and MAC addressing within a local network. Layer 4 handles end-to-end transport (TCP/UDP). Memorize OSI: Please Do Not Throw Sausage Pizza Away.
Which statement about ICMP is correct?
Answer: C — ICMP is a Layer 3 protocol carried directly inside IP packets
C is right: ICMP is IP protocol number 1 and rides directly inside IP at Layer 3, with no transport header and no ports. A and D attach it to TCP, which is the most common misconception. B borrows the echo service port from an unrelated legacy TCP/UDP service. Ping and traceroute rely on ICMP echo and TTL-expired messages.
Which is true of broadcast traffic in a switched LAN?
Answer: C — Switches flood broadcasts within a VLAN; routers do not forward them
C is right: a switch floods a broadcast out every port in the same VLAN, and the router or Layer 3 boundary stops it, which is what makes a VLAN a broadcast domain. A and B reverse the roles, a classic direction-reversal trap. D is wrong because routers do not forward broadcasts by default.
4 cards from the 36 in this chapter.
What is a MAC address and how is it formatted?
48-bit hardware address, written as 6 hex bytes (e.g., 00:1A:2B:3C:4D:5E). First 24 bits = OUI (vendor); last 24 bits = device-specific.
How does SD-WAN differ from SDN in what each one controls and where it is deployed?
SDN separates the control plane from the data plane and centralises forwarding decisions in a controller, usually inside one campus or data centre fabric. SD-WAN applies that same centralised, policy-driven control to wide area links across geographically distributed sites, steering application traffic over broadband, MPLS or cellular based on policy and current path quality.
What is a virtual switch (vSwitch)?
Software switch inside a hypervisor (e.g., vSwitch in ESXi, virtual switch in Hyper-V). Connects VMs to each other and uplinks.
What is a CDN?
Content Delivery Network — geographically distributed servers caching content closer to users. Reduces latency, offloads origin servers.
These are a sample. The full Networking Concepts chapter runs 67 items with per-chapter progress tracking, on the web and in the iOS app.
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