Examworthyexamworthy.comCompTIA Network+ (N10-009) cheat sheet
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At a glance
Format: Multiple choice and performance-based
Domain weight map
Heaviest first - spend your time hereHow this exam thinks
Network+ rewards structured reasoning about how a network fits together and a disciplined troubleshooting method, not memorised trivia about one vendor's boxes.
Spot the trap
Tempting wrong answers, and why they failTempting but wrong
I already suspect a duplex mismatch, so the efficient move is to hard-code both interfaces to the same speed and duplex right away.
Why it fails
That is the eventual corrective action, but implementing a change comes only after the theory has been tested and a plan of action has been established. Jumping straight to the fix skips the required test step.
Network Troubleshooting
Tempting but wrong
A /28 sounds right for six usable hosts because it is one of the smaller subnets.
Why it fails
A /28 leaves four host bits, giving 16 addresses and 14 usable hosts. That is a single host bit too many and doubles the size needed; the requirement of six usable hosts is met by a /29, which leaves three host bits.
Networking Concepts
Tempting but wrong
PC-A cannot reach PC-B in another VLAN, so I just need an 802.1Q trunk between the switchports to connect the two VLANs.
Why it fails
A trunk multiplexes several VLANs onto one switch-to-switch link so their tags survive the hop. It does not route packets from one VLAN subnet into another. Crossing subnets still needs a Layer 3 device.
Network Implementation
Tempting but wrong
A non-default read-only community string on SNMPv2c keeps the traffic private in transit.
Why it fails
A non-default community is safer than 'public', but SNMPv2c still carries the community string and message payload in cleartext, so nothing is encrypted on the wire. Confidentiality needs SNMPv3 authPriv.
Network Operations
Tempting but wrong
Reading captured credentials is really an integrity problem, because an attacker who reads them could later modify the account.
Why it fails
Integrity concerns unauthorised alteration of data. Capturing readable credentials exposes them but does not change any stored value, so the principle harmed is confidentiality, not integrity. A later modification would be a separate event.
Network Security
Tempting but wrong
Gathering symptoms and asking what changed is really the start of establishing a theory of probable cause.
Why it fails
Forming a theory is closely related and therefore tempting, but a probable cause can only be proposed after the symptoms have first been gathered and understood. That gathering is the identify-the-problem step.
Network Troubleshooting
Tempting but wrong
An fe80 address is a unique local address meant for private site-wide routing.
Why it fails
Unique local addresses use fc00::/7, commonly fd00::/8, for private routing within a site. It is a tempting private analogue, but the fe80 prefix marks a link-local address confined to a single link, not a ULA.
Networking Concepts
Tempting but wrong
Enabling Spanning Tree Protocol for both VLANs will open a forwarding path so the two VLANs can talk.
Why it fails
STP manages forwarding paths, but only to prevent Layer 2 loops within a single broadcast domain. It never routes traffic between two different VLAN subnets, which is a Layer 3 job.
Network Implementation
Key terms
Exam-day rules
- Read the last line of the question first. It tells you what is actually being asked, so you can read the scenario looking for the answer rather than absorbing every detail.
- Choose the single best option, not merely a correct one. Several options are often true; the exam wants the best fit for the stated requirement, such as the exact host count or the band in use.
- On troubleshooting questions, respect the order of the seven steps. The trap is a later step offered too early: after a theory you test it, and you verify before you document.
- Check the port and the transport together. A right port number with the wrong transport (or two ports swapped) is a classic distractor, so read DNS as UDP 53, not just 53.
- For subnetting, work from the required usable hosts to the prefix and pick the smallest block that fits. Usable hosts are two to the host bits minus two for network and broadcast.
Revision schedule
- Day 1Map the blueprint and book a date
- Weeks 1-2Lock the concepts foundation (Networking Concepts)
- Weeks 2-3Build the network (Network Implementation)
- Weeks 3-4Operate and secure it (Network Operations and Security)
- Week 4Drill troubleshooting until the method is automatic