CSLB General Building (B) — All Questions
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According to the structured troubleshooting methodology, what is the first step when addressing a network problem?
- a.Implement the solution immediately
- b.Identify the problem and gather information✓
- c.Document findings and outcomes
- d.Escalate to the vendor
The methodology begins with identifying the problem by gathering information, questioning users, and determining the scope. Jumping straight to solutions risks fixing the wrong thing. Later steps include establishing a theory, testing it, and documenting.
After establishing a theory of probable cause, what is the next step in the troubleshooting process?
- a.Document the solution
- b.Establish a plan of action
- c.Test the theory to determine the cause✓
- d.Verify full system functionality
Once a theory of probable cause is formed, the next step is to test that theory to confirm or refute it. If confirmed, a plan of action follows; if not, a new theory is formed. This disciplined loop prevents wasted effort.
A user cannot reach any website by name but can ping external IP addresses directly. Which service is most likely misconfigured?
- a.DNS✓
- b.DHCP
- c.STP
- d.NTP
Being able to ping IPs but not resolve names points to a DNS problem, since name resolution is failing while basic IP connectivity works. Checking the client's DNS server settings is the logical next step. This isolates the layer where the fault lies.
A client receives an address in the 169.254.x.x range. What does this most likely indicate?
- a.A correctly assigned public IP
- b.A static IP misconfiguration
- c.Successful DNS resolution
- d.Failure to reach a DHCP server✓
A 169.254.x.x APIPA address indicates the client could not obtain an address from a DHCP server and self-assigned a link-local address. This points to a DHCP or connectivity problem. Such a host can only communicate on the local link.
Which command-line tool traces the path packets take to a destination, revealing each hop along the way?
- a.ping
- b.traceroute✓
- c.nslookup
- d.arp
Traceroute (or tracert on Windows) maps each router hop between source and destination, helping locate where connectivity breaks or slows. It works by incrementing the TTL to elicit responses from intermediate routers. It complements ping for path analysis.
Two devices on the same subnet cannot communicate, and one shows a duplicate IP address error. What is the likely cause?
- a.A routing loop
- b.A DNS misconfiguration
- c.An IP address conflict✓
- d.An expired SSL certificate
A duplicate IP address error indicates two devices have been assigned the same IP, causing an address conflict that disrupts communication. Resolving it means reassigning one device, often via DHCP reservation or corrected static settings. ARP entries may need clearing afterward.
A fiber link shows very high signal loss and intermittent connectivity. Which physical issue is a likely cause?
- a.A dirty or damaged fiber connector✓
- b.An incorrect VLAN assignment
- c.A missing default gateway
- d.A DHCP scope exhaustion
Dirty, scratched, or damaged fiber connectors cause high signal attenuation and intermittent link problems. Cleaning connectors and inspecting for damage is a standard first check. Optical power meters help quantify the loss.
Users on one switch experience slow performance, and the interface shows a rising count of CRC errors. What does this most likely indicate?
- a.A DNS resolution delay
- b.An exhausted DHCP scope
- c.A misconfigured default route
- d.A cabling or physical layer fault✓
Rising CRC errors point to a physical layer problem such as a damaged cable, bad connector, or electromagnetic interference corrupting frames. Replacing the cable and checking for interference sources is warranted. CRC errors indicate frames arriving corrupted.
Which tool would a technician use to verify that a newly terminated Ethernet cable has correct pinouts and no opens or shorts?
- a.Tone generator
- b.Cable tester✓
- c.Loopback plug
- d.Spectrum analyzer
A cable tester checks continuity, correct pin mapping, and faults such as opens, shorts, or miswires on a terminated cable. It confirms the termination follows the intended standard. A tone generator, by contrast, helps trace and locate cables.
A wireless client experiences a weak signal and frequent disconnects far from the access point. Which term describes this coverage limitation?
- a.Channel overlap
- b.Jitter
- c.Low signal-to-noise ratio / attenuation✓
- d.Broadcast storm
A weak signal at distance reflects attenuation and a low signal-to-noise ratio, degrading throughput and causing disconnects. Solutions include repositioning the AP, adding access points, or adjusting antennas. A site survey helps map coverage gaps.
Which command displays a host's current IP configuration, including address, subnet mask, and default gateway, on Windows?
- a.ipconfig✓
- b.ping
- c.route add
- d.telnet
The ipconfig command on Windows displays the host's IP address, subnet mask, and default gateway, with /all showing DNS and DHCP details. The equivalent on Linux is ifconfig or ip addr. It is a first step in verifying local configuration.
A network experiences a sudden broadcast storm after a technician added a second cable between two switches. What is the most likely cause?
- a.A DNS misconfiguration
- b.An expired DHCP lease
- c.An incorrect subnet mask
- d.A switching loop from a redundant link without STP✓
Adding a redundant link between switches without a working Spanning Tree Protocol creates a Layer 2 loop, producing a broadcast storm. Enabling or verifying STP resolves it. Broadcast storms rapidly saturate switch bandwidth and CPU.
Which utility resolves a hostname to its IP address and can query specific DNS record types?
- a.ping
- b.nslookup✓
- c.ipconfig
- d.netstat
The nslookup utility queries DNS servers to resolve hostnames and can request specific record types such as MX or CNAME. It is invaluable for diagnosing name-resolution issues. The dig command offers similar functionality on Unix-like systems.
A user reports they can access internal resources but not the internet. Other users are unaffected. What should the technician check first on that host?
- a.The entire building's fiber uplink
- b.The core router's routing table
- c.The host's default gateway and DNS settings✓
- d.The ISP's SLA compliance
Because only one user is affected, the problem is likely local to that host, so checking its default gateway and DNS settings comes first. A missing or wrong gateway would block internet access while local resources on the same subnet remain reachable. Isolating scope narrows the fault quickly.
Which command tests basic reachability to a remote host by sending ICMP echo requests?
- a.ping✓
- b.tracert
- c.arp
- d.nbtstat
The ping command sends ICMP echo requests and measures replies to test basic reachability and round-trip time. Successful replies confirm Layer 3 connectivity. Lack of replies may indicate a down host, filtering, or a routing problem.
An access switch port connected to a PC keeps going into an err-disabled state. Which security feature most likely triggered this?
- a.Quality of Service
- b.Link aggregation
- c.Spanning tree root guard
- d.Port security violation✓
A port security violation can place a port into err-disabled state when it detects more MAC addresses than allowed. Reviewing the configured maximum and violation mode reveals the cause. Clearing the condition and correcting the setup restores the port.
Intermittent connectivity affects devices only during business hours, correlating with heavy equipment operation nearby. Which cabling issue is the likely culprit?
- a.Incorrect DNS server
- b.Electromagnetic interference (EMI) on copper cabling✓
- c.Exhausted DHCP scope
- d.A duplicate default gateway
Interference from nearby heavy equipment induces EMI on unshielded copper cabling, causing errors and intermittent connectivity that tracks with equipment use. Rerouting cable away from the source or using shielded cable or fiber resolves it. The time-based correlation is a strong clue.
A pair of switch ports negotiated a duplex mismatch. Which symptom is most characteristic of this condition?
- a.Complete loss of link
- b.APIPA addressing
- c.Late collisions and slow throughput✓
- d.DNS resolution failures
A duplex mismatch, where one side is full and the other half duplex, typically causes late collisions, frame errors, and poor throughput rather than a total link failure. Setting both ends to the same duplex, or both to autonegotiate, resolves it. Late collisions on a full-duplex link are a telltale sign.
After confirming a fix resolves the reported issue, which troubleshooting step should be performed next?
- a.Verify full system functionality and implement preventive measures✓
- b.Immediately close the ticket without testing
- c.Reboot every device on the network
- d.Escalate the issue to management
After implementing a fix, the technician should verify full system functionality and, if applicable, apply preventive measures to keep the issue from recurring. This confirms the solution truly worked end to end. Documentation follows as the final step.
A technician suspects a specific cable among many in a bundle. Which tool pair helps locate and identify that individual cable?
- a.Multimeter and OTDR
- b.Tone generator and inductive probe✓
- c.Cable tester and loopback plug
- d.Protocol analyzer and syslog
A tone generator places a signal on a wire, and the inductive probe detects that tone to locate and identify the specific cable within a bundle. This is standard practice for tracing cables in patch panels or ceilings. It complements continuity testing.
A server's throughput is far below the link's rated speed, and interface counters show many output drops during peak traffic. What is the likely cause?
- a.A DNS misconfiguration
- b.An incorrect default gateway
- c.A duplicate IP address
- d.Congestion causing the interface queue to overflow✓
Output drops during peak traffic indicate the interface queue is overflowing due to congestion, so packets are discarded when buffers fill. QoS, increased capacity, or traffic shaping can relieve it. The correlation with peak load confirms congestion rather than a config error.
Which command shows active TCP/UDP connections and listening ports on a local host?
- a.ping
- b.tracert
- c.netstat✓
- d.arp
The netstat command lists active connections, listening ports, and associated states on the local host. It helps confirm whether a service is listening and which remote endpoints are connected. It is useful for diagnosing application and port issues.
The final step of the troubleshooting methodology is to document the findings, actions, and outcomes. Why is this step important?
- a.It builds a knowledge base that speeds resolution of future similar issues✓
- b.It automatically prevents all future outages
- c.It replaces the need for network monitoring
- d.It eliminates the need for change management
Documenting findings, actions, and outcomes creates a knowledge base that helps resolve similar future problems faster and informs others. It also supports auditing and accountability. Skipping documentation loses valuable troubleshooting insight.
A newly connected device gets no link light and no connectivity, while other ports on the same switch work. What should the technician verify first?
- a.The ISP's routing table
- b.The corporate DNS zone file
- c.The organization's SLA terms
- d.The patch cable and physical port connection✓
With a dead port while neighbors work, the fault is almost certainly local, so the technician should first verify the patch cable and physical connection, swapping the cable and trying another port. A missing link light points to a Layer 1 problem rather than addressing or routing. Confirming physical connectivity comes before higher-layer checks.