Core Network Settings for A+
Short answer
- IP address: identifies the host on the local network. - Subnet mask: indicates which addresses are local vs remote. - Default gateway: where packets leave the local network to reach other networks. - DNS: resolves names to addresses.
Why it appears on the exam
- Given a short symptom and a set of client network fields, select which field is most likely responsible. - Given mismatched address and mask examples, determine whether two hosts can communicate locally.
Key concepts
Concept 1
Required terms
Subnet mask: A value that determines which portion of an IPv4 address refers to the network and which to the host; commonly shown as dotted-decimal like 255.255.255.0. Default gateway: The IP address of the device (usually a router) that forwards traffic to other networks; used when a destination is outside the local subnet. DNS server: A server that resolves hostnames to IP addresses; misconfigured DNS prevents name resolution even if IP connectivity exists.
Example
Symptom: "Can ping other devices on same 192.168.1.x network but not internet." Likely gateway or upstream issue.
Concept 2
How Core Network Settings works
- IP address: identifies the host on the local network. - Subnet mask: indicates which addresses are local vs remote. - Default gateway: where packets leave the local network to reach other networks. - DNS: resolves names to addresses.
Example
Symptom: "Can access web by IP but not by hostname." Likely DNS problem.
Concept 3
Common confusion
- Interpreting inability to reach internet as always a DNS problem. Some symptoms require checking multiple fields in order (address/mask, then gateway, then DNS). - Assuming a correct-looking gateway IP guarantees route; the gateway device itself or upstream routing may be failing.
Example
Symptom: "Cannot reach other devices on LAN." Check IP and subnet mask for compatibility.
Concept 4
Core 1 (220-1201) question cues
Given a short symptom and a set of client network fields, select which field is most likely responsible; Given mismatched address and mask examples, determine whether two hosts can communicate locally.
Example
Symptom: "Can ping other devices on same 192.168.1.x network but not internet." Likely gateway or upstream issue.
Sample questions
Select an answer to reveal the explanation. For tracked practice and weak-area review, use the Cultiv8 app.
Q1.A technician is troubleshooting this situation: Symptom: "Cannot reach other devices on LAN." Check IP and subnet mask for compatibility. What should they identify?
Q2.For this A+ objective, the scenario says: Symptom: "Can access web by IP but not by hostname." Likely DNS problem. What is the best match?
Q3.An A+ support scenario describes this situation: Symptom: "Cannot reach other devices on LAN." Check IP and subnet mask for compatibility. Which answer fits best?
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