200-901 Network Fundamentals — 100 Questions

Question 1

Which of the following is a private IPv4 address range as defined by RFC 1918?

Accepted Answer

192.168.0.0/16. RFC 1918 defines private IPv4 address ranges that are not routable on the public Internet. The 192.168.0.0/16 range (192.168.0.0 – 192.168.255.255) is explicitly listed in RFC 1918 as a Class C private block, making option A correct.

Answer

172.32.0.0/12

Answer

172.15.0.0/12

Answer

11.0.0.0/8

Question 2

A network engineer is configuring a wireless network for a hospital that requires high throughput and minimal interference from neighboring networks. Which set of 2.4 GHz channels should be used for non-overlapping coverage?

Accepted Answer

1, 6, 11. In the 2.4 GHz ISM band, channels 1, 6, and 11 are the only three non-overlapping channels, each separated by 25 MHz, which prevents co-channel interference. This configuration maximizes throughput and minimizes interference from neighboring networks, making it ideal for high-density environments like hospitals.

Answer

2, 7, 12

Answer

1, 5, 9

Answer

1, 3, 5

Question 3

A network administrator notices that a host with IP 192.168.1.10/25 cannot communicate with a host at 192.168.1.200/25. What is the most likely reason?

Accepted Answer

The subnet mask is incorrect; they are on different subnets.. With a /25 mask, the subnet range is 192.168.1.0–192.168.1.127, so 192.168.1.10 is in that subnet while 192.168.1.200 falls in the next subnet (192.168.1.128–192.168.1.255). Hosts on different subnets cannot communicate directly at Layer 2, which explains the failure.

Answer

The default gateway is missing.

Answer

The ARP cache is corrupted.

Answer

The hosts are using different DNS servers.

Question 4

Which of the following is a private IPv4 address range as defined by RFC 1918?

Accepted Answer

192.168.0.0/16. RFC 1918 reserves the 192.168.0.0/16 block (192.168.0.0 – 192.168.255.255) as a private IPv4 address range, meaning these addresses are not routable on the public internet and are intended for use within private networks.

Answer

169.254.0.0/16

Answer

11.0.0.0/8

Answer

172.32.0.0/12

Question 5

A network administrator is deploying a wireless network that supports the latest security standards and high throughput. Which TWO of the following are true regarding Wi-Fi 6 (802.11ax) compared to Wi-Fi 5 (802.11ac)?

Accepted Answer

Uses OFDMA for improved efficiency. Option A is correct because Wi-Fi 6 (802.11ax) introduces OFDMA (Orthogonal Frequency-Division Multiple Access), which subdivides channels into resource units so multiple clients can transmit simultaneously, greatly improving spectral efficiency over Wi-Fi 5's OFDM-only approach. Option C is correct because Wi-Fi 6 certification requires WPA3 support as the mandatory security standard, replacing WPA2 and delivering stronger authentication (SAE) and encryption. Option B is wrong because Wi-Fi 6 supports 20, 40, 80, and 160 MHz channels, not only 20 MHz. Option D is wrong because Wi-Fi 6's maximum theoretical throughput is higher than Wi-Fi 5's, not lower. Option E is wrong because Wi-Fi 6 operates on both 2.4 GHz and 5 GHz bands (and 6 GHz in Wi-Fi 6E), not only 5 GHz.

Answer

Uses only 20 MHz channels

Answer

Maximum theoretical speed is lower than Wi-Fi 5

Answer

Operates only on the 5 GHz band

Question 6

Which of the following is a private IPv4 address range as defined by RFC 1918?

Accepted Answer

10.0.0.0/8. RFC 1918 defines three private IPv4 address ranges: 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16. Option A, 10.0.0.0/8, is one of these ranges. The other options are incorrect because they either fall outside the defined private ranges or use incorrect subnet masks.

Answer

172.32.0.0/12

Answer

172.15.0.0/12

Answer

192.167.0.0/16

Question 7

Which DNS record type is used to map a domain name to an IPv6 address?

Accepted Answer

AAAA. The AAAA record is used for IPv6 address mapping.

Answer

CNAME

Answer

MX

Answer

A

Question 8

Which of the following is a private IPv4 address range as defined by RFC 1918?

Accepted Answer

172.16.0.0/12. RFC 1918 defines the private IPv4 address range 172.16.0.0/12, which includes addresses from 172.16.0.0 to 172.31.255.255. These addresses are reserved for use within private networks and are not routable on the public internet.

Answer

192.167.0.0/16

Answer

11.0.0.0/8

Answer

172.32.0.0/12

Question 9

Which wireless standard is commonly known as Wi-Fi 6 and operates in both 2.4 GHz and 5 GHz bands?

Accepted Answer

802.11ax. 802.11ax, marketed as Wi-Fi 6, is the correct answer because it is the only standard among the options that operates in both the 2.4 GHz and 5 GHz bands and introduces OFDMA, 1024-QAM, and improved MU-MIMO for higher efficiency and throughput. Wi-Fi 6 is backward compatible with previous standards but requires compatible clients to leverage its full capabilities.

Answer

802.11g

Answer

802.11n

Answer

802.11ac

Question 10

Which non-overlapping channels are available in the 2.4 GHz band for Wi-Fi to minimize interference?

Accepted Answer

1, 6, 11. Channels 1, 6, and 11 are the only non-overlapping channels in 2.4 GHz.

Answer

1, 3, 5, 7, 9, 11

Answer

1, 5, 9, 13

Answer

2, 7, 12

Question 11

Which of the following is a private IPv4 address range as defined by RFC 1918?

Accepted Answer

10.0.0.0/8. (10.0.0.0/8) is correct because RFC 1918 reserves this range, along with 172.16.0.0/12 and 192.168.0.0/16, for private IPv4 addressing. These addresses are not routable on the public internet and are intended for use within private networks, such as corporate LANs or home networks.

Answer

169.254.0.0/16

Answer

192.167.0.0/16

Answer

172.32.0.0/16

Question 12

A network administrator is configuring a DNS server. Which TWO DNS record types are used for IPv6 address resolution?

Accepted Answer

PTR record. The AAAA record (option D) maps a hostname to a 128-bit IPv6 address, analogous to the A record for IPv4. The PTR record (option C) performs reverse DNS lookup, mapping an IPv6 address to a hostname, which is essential for IPv6 address resolution in scenarios like logging or mail server verification.

Answer

MX record

Answer

CNAME record

Answer

A record

Question 13

Which THREE of the following are characteristics of the UDP protocol?

Accepted Answer

Used by DNS and DHCP. UDP is a connectionless transport layer protocol that provides minimal overhead, making it ideal for applications like DNS and DHCP that require fast, lightweight communication. DNS uses UDP for queries (port 53) and DHCP uses UDP for client-server exchanges (ports 67/68) because they can tolerate occasional packet loss and benefit from the reduced latency.

Answer

Connection-oriented

Answer

Reliable delivery

Question 14

A network engineer is designing a wireless network for an office that requires high throughput and minimal interference. Which two channels should be used for the 2.4 GHz band to avoid overlap? (Choose two.)

Accepted Answer

Channel 6. In the 2.4 GHz band, channels 1, 6, and 11 are the only non-overlapping channels when using 20 MHz channel spacing, as each channel occupies 22 MHz of bandwidth and these three are spaced 25 MHz apart. Channels 1 and 6 are correct because they do not overlap, minimizing co-channel interference and maximizing throughput.

Answer

Channel 11

Answer

Channel 9

Answer

Channel 3

Question 15

A software-defined networking (SDN) controller is being deployed to manage network devices. Which two components are part of the SDN architecture? (Choose two.)

Accepted Answer

Data plane. In SDN architecture, the Data plane (A) is the correct component because it consists of the network devices (switches, routers) that actually forward packets based on rules installed by the controller, and the Control plane (B) is correct because it is the logically centralized SDN controller that computes and distributes forwarding decisions to the data plane. These two planes form the foundational split that defines SDN: the control plane is decoupled from the data plane, with the controller programming the underlying forwarding hardware via protocols such as OpenFlow. The Application plane (C) is not one of the two components asked for here, as it refers to SDN applications that sit above the controller via northbound APIs rather than being a core architectural plane in this context. Forwarding plane (D) is simply another name for the data plane, so it is not a separate correct component. Management plane (E) is not part of the SDN architecture's core planes; it handles administrative functions like monitoring and configuration and is not the decoupled control/data plane pair described.

Answer

Application plane

Answer

Forwarding plane

Answer

Management plane

Question 16

An engineer is configuring a new IPv4 subnet with the address 172.16.5.0/25. Which three statements are true about this subnet? (Choose three.)

Accepted Answer

There are 126 usable host addresses.. A /25 prefix length corresponds to a subnet mask of 255.255.255.128, which provides 2^(32-25) - 2 = 128 - 2 = 126 usable host addresses. The network address is 172.16.5.0, and the broadcast address is 172.16.5.127, leaving addresses 172.16.5.1 through 172.16.5.126 for hosts.

Answer

The subnet mask is 255.255.255.192.

Answer

The network address is 172.16.5.128.

Question 17

A network engineer is analyzing traffic and observes that a client and server have completed the TCP three-way handshake. The client now needs to gracefully terminate the connection and ensure the server receives all outstanding data. Which sequence of TCP flags should the client send to initiate this teardown?

Accepted Answer

FIN, then ACK, then FIN, then ACK. A graceful TCP connection teardown uses a four-way handshake: the initiating side sends FIN, the other side acknowledges with ACK, then the other side sends its own FIN, and the first side acknowledges with ACK. This ensures both directions are closed and all data is delivered. The sequence in the correct option matches this process exactly.

Answer

SYN, then ACK, then FIN

Answer

ACK, then FIN, then ACK

Answer

RST, then ACK

Question 18

A network engineer is designing a solution that uses a Cisco SD-WAN controller. The engineer needs to programmatically retrieve the list of vEdge devices and their current status from the controller's API. The API is REST-based and requires authentication. Which two actions must the engineer perform to successfully authenticate and retrieve the data? (Choose two.)

Accepted Answer

Obtain a session token by sending a POST request to the /j_security_check endpoint with a JSON payload containing the username and password.. The Cisco SD-WAN vManage API requires session-based authentication. The engineer must first POST credentials to /j_security_check to obtain a JSESSIONID cookie, then include that cookie in subsequent GET requests to endpoints like /dataservice/device. This two-step process is necessary because the API does not support Basic Auth or API keys.

Answer

Send a POST request to /dataservice/device with the username and password in the body to retrieve the device list.

Answer

Generate an API key from the vManage GUI and include it in the X-API-Key header for all requests.

Answer

Use HTTP Basic Authentication with the username and password encoded in Base64 in the Authorization header for every request.

Question 19

A developer is writing a Python script that must retrieve the current time from a remote server without establishing a persistent connection or verifying delivery. Which transport protocol and port should the script use to send a single small request and receive a single small response?

Accepted Answer

UDP with an ephemeral destination port. The requirement is for a simple request/response exchange without a persistent connection or delivery verification. UDP provides connectionless, best-effort datagram delivery, which matches the described behavior. TCP would introduce a three-way handshake and reliability mechanisms that are unnecessary here. The port number is not the primary concern; the transport protocol is what matters for the stated constraints.

Answer

TCP port 123

Answer

UDP port 123

Answer

UDP port 69

Question 20

A network engineer needs to connect two switches in the same building so that devices on both switches can communicate as if they were on the same local area network. The engineer wants to avoid any routing between the two switches. Which type of connection should be used?

Accepted Answer

A Layer 2 trunk or access link in the same VLAN. Extending a single local area network across two switches requires a Layer 2 connection that places both switches in the same broadcast domain. A link configured for the same VLAN, whether as an access port or a trunk carrying that VLAN, achieves this without routing. The other options either introduce routing or are intended for different purposes such as carrying multiple VLANs or connecting endpoints, so they do not satisfy the requirement.

Answer

A routed link with OSPF enabled

Answer

A trunk link carrying multiple VLANs

Answer

An access link configured as a trunk