Worth 23% of the CompTIA Network+ (N10-009) exam. CertClue has 89 questions on this objective.
Topology questions ask you to match a described layout to its name, or to identify which design suits a stated requirement. Modern data centre designs appear alongside the classic shapes.
Exam tip. Spine and leaf is the expected answer whenever a question emphasises east-west traffic or consistent latency between any two servers in a data centre.
The OSI model underpins a large share of Network+ questions. You need the layer order, what each layer does, and which devices, protocols and problems belong to each. Most troubleshooting questions are really asking which layer has failed.
Exam tip. Work bottom up. Confirm physical connectivity before addressing, and addressing before ports. Most exam scenarios expect you to name the lowest layer that could explain every symptom given.
Encapsulation explains what each layer adds to data on the way out and strips on the way in. Knowing the protocol data unit name at each layer makes several exam questions immediate.
Exam tip. Jumbo frame questions turn on consistency: if any device in the path uses the standard MTU, large frames are dropped without an obvious error. Enable them end to end or not at all.
Subnetting is the most mathematically demanding part of Network+. You need to convert between CIDR notation and subnet masks, and calculate usable hosts and network boundaries quickly.
Exam tip. Memorise the /24 to /30 block sizes cold. Most subnetting questions are solved by identifying the block size, finding the boundary below the given address, and reading off the range.
Objective 1.3 covers cloud from a networking perspective: how you connect to it, how it is segmented, and the service and deployment models.
Exam tip. A private dedicated circuit to a cloud provider is the answer whenever a question stresses consistent latency or bandwidth guarantees that the public internet cannot offer.
Traffic type questions describe a delivery pattern and expect the term. The distinguishing factor is how many recipients receive the traffic and how they are selected.
Exam tip. Anycast is the answer whenever the scenario involves the same address being served from multiple geographic locations, which is how public DNS and CDNs work.
Media questions revolve around distance, speed and interference. The 100 metre copper limit and the single-mode versus multi-mode distinction decide most of them.
Exam tip. Mismatched transceivers are a common scenario: the link stays down because one end is single-mode and the other multi-mode, or the wavelengths differ. Both ends must match.
Objective 1.2 covers the devices in a modern network. Match the described function to the appliance, and know which are physical, virtual or cloud-delivered.
Exam tip. IDS versus IPS turns entirely on whether the device is inline and takes action. If the requirement is to stop traffic rather than report it, only IPS qualifies.
Network+ tests port numbers more precisely than A+, including which transport protocol each uses. Learn insecure and secure pairs together, because questions usually ask for the secure replacement.
Exam tip. Know which protocols use UDP: DNS queries, DHCP, TFTP, SNMP, syslog and voice traffic. Questions often hinge on the transport protocol rather than the port number itself.
Free, with the answer and the reasoning. No account needed.
1. Which port does DNS use when a response exceeds the size that fits in a single UDP datagram?
DNS falls back to TCP on the same port 53 for zone transfers and responses too large for UDP. Port 68 is the DHCP client, 443 is HTTPS, and 161 is SNMP polling.
2. A network engineer is troubleshooting a connectivity issue and wants to confirm whether the problem lies with physical cabling or something higher up the stack. Which OSI layer deals with the actual electrical signals, cabling, and connectors?
Layer 1 (Physical) covers the actual transmission medium, including cabling, connectors, and electrical or optical signals. Layer 3 handles logical addressing and routing, Layer 4 handles end-to-end transport, and Layer 7 is where user-facing applications interact with the network.
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