N10-009 Practice Test 23 — 15 Questions

Question 1

A user reports that they cannot access the internal web server by its fully qualified domain name (intranet.company.com). The workstation's IP configuration shows a DNS server of 8.8.8.8, but the internal DNS server is 10.0.0.10. The user can successfully ping the server's IP address (10.0.0.50). What is the MOST likely cause of the issue?

Accepted Answer

A: The workstation is using the wrong DNS server address. The workstation's DNS server is set to 8.8.8.8 (a public Google DNS server), which cannot resolve the internal domain name 'intranet.company.com' because that zone is only hosted on the internal DNS server at 10.0.0.10. Since the user can ping the server's IP address (10.0.0.50), network connectivity is fine, confirming the issue is name resolution. The most likely cause is that the workstation is using the wrong DNS server address.

Answer

B: The subnet mask on the workstation is incorrect

Answer

C: The network cable is faulty

Answer

D: The default gateway is misconfigured

Question 2

Which of the following is the primary function of a subnet mask in IPv4 networking?

Accepted Answer

It determines the network portion of an IP address. The subnet mask's primary function is to distinguish the network portion from the host portion of an IPv4 address. By applying a bitwise AND operation between the IP address and the subnet mask, the network address is derived, which is essential for routing decisions. Without this separation, devices cannot determine whether a destination is local or requires forwarding through a router.

Answer

It identifies the default gateway for a subnet

Answer

It provides encryption for data in transit

Answer

It maps IP addresses to MAC addresses

Question 3

A network engineer is designing a new IPv6 addressing scheme. The company has been assigned a /48 prefix and needs to support up to 250 subnets. Which subnet size should be used to minimize waste while meeting the requirement?

Accepted Answer

/56. A /56 subnet provides 256 subnets (2^(56-48) = 2^8 = 256), which meets the requirement of up to 250 subnets with minimal waste. A /48 prefix is the site-level allocation, and using a /56 subnet mask leaves 8 bits for subnetting, offering exactly the needed capacity without over-allocating address space.

Answer

/52

Answer

/64

Answer

/60

Question 4

A network engineer is planning a wireless LAN for an open office with 50 users. To maximize performance by using multiple non-overlapping channels, which frequency band should be primarily used?

Accepted Answer

5 GHz. The 5 GHz band is the best choice for maximizing performance in an open office with 50 users because it offers up to 23 non-overlapping channels (using 20 MHz channels) compared to only 3 in the 2.4 GHz band. This allows for better channel reuse, reduced co-channel interference, and higher aggregate throughput in a dense user environment.

Answer

2.4 GHz

Answer

6 GHz

Answer

900 MHz

Question 5

A network engineer has configured an IPsec site-to-site VPN between two offices. The tunnel is established and shows as active. However, users at the branch office (10.0.1.0/24) cannot reach servers at the main office (192.168.1.0/24). Both routers have the correct VPN policies and firewall rules permitting IPsec traffic. What should the engineer check next?

Accepted Answer

B) That the routing tables on both routers include routes to the remote subnet. The tunnel being active means Phase 1 and Phase 2 of IPsec are established, but traffic still cannot flow because the routers lack routes to the remote subnets. Without a route for 10.0.1.0/24 on the main office router (or 192.168.1.0/24 on the branch router), packets will be dropped or sent out the wrong interface, even though the VPN policy and firewall rules are correct. The engineer must verify that static routes or a dynamic routing protocol (e.g., OSPF over the tunnel) are in place to direct traffic into the IPsec tunnel interface.

Answer

A) That the DNS server addresses are correctly configured

Answer

C) That the MTU size is set to 1500 on both ends

Answer

D) That the SSID is correctly configured on the access points

Question 6

At which layer of the OSI model does a device provide flow control, error detection, and recovery for end-to-end communication?

Accepted Answer

A: Transport layer. The Transport layer (Layer 4) is responsible for end-to-end communication between source and destination hosts. It provides flow control (e.g., TCP's sliding window mechanism), error detection (via checksums in TCP and UDP headers), and recovery (through TCP retransmission of lost segments). These functions ensure reliable data delivery across the network, distinguishing it from lower layers that handle hop-by-hop or link-local tasks.

Answer

B: Network layer

Answer

C: Data Link layer

Answer

D: Session layer

Question 7

A network engineer is designing a network and needs to ensure that broadcast traffic is contained within a single broadcast domain. Which of the following devices should be used to create these separate broadcast domains?

Accepted Answer

Router. A router operates at Layer 3 of the OSI model and does not forward broadcast frames by default, making it the correct device to segment a network into separate broadcast domains. Each interface on a router creates a distinct broadcast domain, ensuring that broadcast traffic is contained within that interface's subnet.

Answer

Hub

Answer

Bridge

Answer

Switch

Question 8

A security engineer is configuring a firewall to protect an internal network. The requirement is that internal users can initiate connections to the internet, but external hosts should not be able to initiate connections to internal hosts unless the internal host first requested the connection. Which firewall technology should be used?

Accepted Answer

Stateful inspection. Stateful inspection (B) tracks the state of active connections by maintaining a state table that records source/destination IPs, ports, and sequence numbers. It allows return traffic for connections initiated from the internal network while blocking unsolicited inbound traffic, which directly matches the requirement that external hosts cannot initiate connections unless the internal host requested them first.

Answer

Stateless packet filtering

Answer

Application proxy

Answer

Packet filtering based on ACL only

Question 9

A network engineer needs to assign IP addresses to a new subnet that will support exactly 25 devices. Which subnet mask would provide the minimum number of usable host addresses while still accommodating the requirement?

Accepted Answer

255.255.255.224 (/27). Option B (255.255.255.224, /27) provides 32 total addresses per subnet, with 30 usable host addresses (2^(32-27)-2 = 30). This is the smallest subnet that can accommodate exactly 25 devices, as /28 yields only 14 usable hosts and /26 yields 62, which is excessive.

Answer

255.255.255.240 (/28)

Answer

255.255.255.192 (/26)

Answer

255.255.255.128 (/25)

Question 10

Which of the following devices operates at Layer 3 of the OSI model and makes forwarding decisions based on destination IP addresses?

Accepted Answer

Router. A router operates at Layer 3 (Network layer) of the OSI model and uses the destination IP address in the packet header to make forwarding decisions. It maintains a routing table (e.g., via OSPF, EIGRP, or static routes) to determine the next-hop interface for each packet, enabling communication between different subnets or VLANs.

Answer

Switch

Answer

Bridge

Answer

Hub

Question 11

A user reports intermittent connectivity issues. The technician notices that the link lights on both the PC and the switch are solid, but the user experiences periodic drops. The technician runs a cable test and finds that one pair of wires is open. Which standard is the cable likely violating?

Accepted Answer

TIA/EIA-568. The TIA/EIA-568 standard specifies the wiring pinouts and performance requirements for twisted-pair cabling, including that all four pairs must be properly terminated and continuous. An open pair violates this standard because it breaks the required electrical continuity, leading to signal degradation and intermittent connectivity. The solid link lights indicate basic electrical connectivity on some pairs, but the open pair causes periodic drops when the network attempts to use that pair for data transmission.

Answer

IEEE 802.3

Answer

ISO 9001

Answer

RFC 1918

Question 12

A network engineer needs to update the firmware on dozens of access points located across multiple office floors. The APs are managed by a central wireless controller. Which protocol should the controller use to transfer the firmware file to each AP?

Accepted Answer

TFTP. The correct answer is TFTP (Trivial File Transfer Protocol). Wireless LAN controllers (WLCs) use TFTP to push firmware images to lightweight access points (APs) because TFTP is lightweight, connectionless, and requires minimal memory and processing overhead on the AP. This makes it ideal for the simple, one-way file transfer of a firmware binary during the AP boot or upgrade process, where the AP acts as a TFTP client and the controller as the server.

Answer

FTP

Answer

HTTP

Answer

SNMP

Question 13

A network administrator needs to securely transfer backup configuration files from a router to a remote server over the internet. Which protocol should be used?

Accepted Answer

SCP. SCP (Secure Copy Protocol) is the correct choice because it provides encrypted file transfers over SSH, ensuring confidentiality and integrity of backup configuration files transmitted over the internet. Unlike TFTP or FTP, SCP authenticates the remote server and encrypts the data in transit, which is essential for secure remote backups.

Answer

TFTP

Answer

FTP

Answer

SNMP

Question 14

A network engineer needs to securely transfer router configuration files to a central backup server. The backup server supports SCP and TFTP. Which protocol should the engineer use?

Accepted Answer

SCP. SCP (Secure Copy Protocol) is the correct choice because it encrypts both the authentication and the data transfer using SSH, ensuring confidentiality and integrity of the router configuration files during transit. TFTP, while simple and often used for network device backups, lacks any encryption or authentication, making it insecure for transferring sensitive configuration data over a network.

Answer

TFTP

Answer

HTTP

Answer

FTP

Question 15

Which of the following IPv6 addresses is a link-local address?

Accepted Answer

fe80::1. Option B (fe80::1) is correct because IPv6 link-local addresses always begin with the prefix fe80::/10, as defined in RFC 4291. These addresses are automatically assigned to every IPv6-enabled interface and are only valid on a single link (subnet), never routed. The address fe80::1 is a common example of a link-local address.

Answer

2001:db8::1

Answer

ff02::1

Answer

2000::/3