Community Q&A
N10-008 — frequently asked questions
Community-vetted answers to 20 common questions about this exam, each traced back to a specific practice question.
General exam questions
20 answers
A network technician is troubleshooting a workstation that cannot access internal resources but can ping the default gateway. Which OSI layer is most likely the issue?
Layer 3 (Network Layer). Since the workstation can ping the default gateway, Layer 1 and Layer 2 are functional. The inability to access internal resources (which typically relies on routing or higher-layer protocols) while maintaining basic connectivity points to a routing issue, ACL misconfiguration, or DNS failure, all residing at Layer 3 or above.
Which subnet mask provides exactly 15 usable IP addresses for a printer network with the least amount of wasted addresses?
255.255.255.240 (/28). A /28 subnet provides 16 total IP addresses (14 usable), which is insufficient. A /27 provides 32 total (30 usable), which covers the 15 printers with the least waste among valid options. Correction: Wait, /28 = 16 total, 14 usable. /27 = 32 total, 30 usable. To get 15 usable, you need at least 17 total addresses. The next power of 2 is 32. So /27 (255.255.255.224) is the correct answer.
Users in a high-density office report intermittent wireless connectivity and slow speeds during peak hours. The WAPs are configured on the same channel. What is the most likely cause?
Co-channel interference (CCI). When multiple WAPs operate on the same channel in close proximity, they contend for airtime, causing collisions and retransmissions. The solution is to configure non-overlapping channels (e.g., 1, 6, 11 for 2.4GHz) or use 5GHz with DFS channels.
Which VPN technology allows a remote user to access only specific internal resources while sending general internet traffic directly to the local ISP?
Split tunneling. This configuration routes only traffic destined for the corporate network through the VPN tunnel, while all other traffic (e.g., web browsing) uses the local internet connection, reducing bandwidth load on the corporate gateway.
A network administrator needs to verify which ports are currently open and listening on a Windows server. Which command should be used?
netstat -an. The 'netstat' command displays active TCP connections, ports on which the computer is listening, Ethernet statistics, the IP routing table, and IPv4/IPv6 statistics. The '-an' flag shows all connections and listening ports in numerical form.
Which BGP attribute is used to influence the path selection for traffic entering an AS, preferring the path with the lowest value?
Multi-Exit Discriminator (MED). MED is an optional non-transitive attribute used to suggest to an external neighbor the preferred path into the AS. Lower values are preferred. It is only compared between routes from the same neighboring AS.
A company requires a disaster recovery site that has no equipment or cabling pre-installed, but has power and cooling. Which site type is this?
Cold site. A cold site provides basic infrastructure (power, cooling, floor space) but lacks hardware, software, and data. It has the lowest cost but the longest recovery time (RTO) compared to warm or hot sites.
Which protocol is used to automatically assign IP addresses and other network configuration parameters to devices on a network?
DHCP (Dynamic Host Configuration Protocol). DHCP uses a DORA process (Discover, Offer, Request, Acknowledge) to dynamically assign IP addresses, subnet masks, default gateways, and DNS servers to clients.
A technician suspects a DNS poisoning attack. Which log should be checked first to verify if clients are being redirected to malicious sites?
DNS Server logs and client resolver cache. Checking the 'ipconfig /displaydns' on affected clients can show cached malicious entries. Server-side logs can reveal unauthorized zone transfers or suspicious query patterns.
Which wireless standard operates exclusively in the 5GHz frequency band and supports MU-MIMO?
802.11ac (Wi-Fi 5). While 802.11n supports 5GHz, it also uses 2.4GHz. 802.11ac was designed specifically for 5GHz to leverage wider channels and MU-MIMO for downlink performance.
What is the primary function of a Layer 2 switch in a network?
Frame forwarding based on MAC addresses. Layer 2 switches use the MAC address table (CAM table) to forward frames only to the specific port where the destination device is located, reducing collision domains and improving efficiency.
Which cable type is most susceptible to electromagnetic interference (EMI) and should be avoided near heavy machinery?
Unshielded Twisted Pair (UTP). UTP relies solely on the twisting of pairs to cancel interference. In high-EMI environments, Shielded Twisted Pair (STP) or fiber optic cabling should be used.
A user can ping an external server by IP address but not by hostname. What is the most likely issue?
DNS resolution failure. Since IP connectivity works (ping by IP succeeds), the issue is isolated to name resolution. Check DNS server settings, DNS server availability, or local hosts file.
Which routing protocol is classified as a hybrid protocol, using both distance-vector and link-state characteristics?
EIGRP (Enhanced Interior Gateway Routing Protocol). EIGRP uses DUAL (Diffusing Update Algorithm) for loop-free paths and sends partial updates like a distance-vector protocol, but maintains a topology table like a link-state protocol.
What is the purpose of 802.1X in a network environment?
Port-based Network Access Control (NAC). 802.1X provides an authentication mechanism for devices trying to connect to a LAN or WLAN. It requires three components: the supplicant (client), authenticator (switch/AP), and authentication server (RADIUS).
Which tool is best suited for capturing and analyzing individual packets on a network segment to troubleshoot protocol issues?
Protocol analyzer (e.g., Wireshark). Packet sniffers capture raw traffic for deep inspection of headers, payloads, and handshakes, which is essential for diagnosing complex protocol failures.
A company is migrating to the cloud but must keep sensitive customer data on-premises due to regulations. Which cloud model is appropriate?
Hybrid cloud. A hybrid model combines on-premises infrastructure (private cloud) with public cloud services, allowing data and applications to be shared between them, meeting compliance while leveraging cloud scalability.
Which port is used for secure email submission by mail clients to a mail server?
- Port 587 is the standard for mail submission with STARTTLS encryption. Port 25 is for server-to-server relay (often blocked by ISPs), and Port 465 is a deprecated but still used legacy SSL port.
What is the effect of enabling 'Spanning Tree Protocol' (STP) on a switch?
Prevents Layer 2 loops. STP actively blocks redundant paths in a switched network to prevent broadcast storms and MAC table instability, while keeping a backup path available if the primary link fails.
Which metric is most critical for real-time VoIP traffic quality?
Jitter. Jitter is the variation in packet arrival time. High jitter causes voice packets to arrive out of order or too late for the jitter buffer, resulting in choppy or garbled audio. Latency and packet loss are also important, but jitter is the primary killer of VoIP quality.