200-901 Network Fundamentals — 25 Questions

Question 1

In the OSI model, which layer is responsible for logical addressing and routing of packets between networks?

Accepted Answer

Layer 3 (Network). Layer 3 (Network layer) handles IP addressing and routing decisions.

Answer

Layer 1 (Physical)

Answer

Layer 4 (Transport)

Answer

Layer 2 (Data Link)

Question 2

Which transport protocol is connection-oriented and ensures reliable delivery through acknowledgments and retransmissions?

Accepted Answer

TCP. TCP is connection-oriented and provides reliability.

Answer

IP

Answer

HTTP

Answer

UDP

Question 3

A DNS AAAA record is used to resolve a hostname to what type of address?

Accepted Answer

IPv6 address. AAAA records map hostnames to IPv6 addresses.

Answer

Mail exchange server

Answer

IPv4 address

Answer

Canonical name alias

Question 4

A network engineer is designing a subnet that needs to support 30 usable hosts. Which subnet mask should be used?

Accepted Answer

255.255.255.224 (/27). (255.255.255.224, /27) provides 5 host bits, yielding 2^5 = 32 total addresses per subnet. Subtracting the network and broadcast addresses leaves exactly 30 usable hosts, meeting the requirement precisely.

Answer

255.255.255.240 (/28)

Answer

255.255.255.0 (/24)

Answer

255.255.255.192 (/26)

Question 5

Which HTTP method is idempotent and used to update a resource by sending the full representation?

Accepted Answer

PUT. PUT is idempotent because making the same request multiple times results in the same server state. It requires the client to send a full representation of the resource, replacing any existing resource at that URI. This aligns with RFC 7231, which defines PUT as a method that creates or replaces the target resource with the enclosed representation.

Answer

DELETE

Answer

POST

Answer

GET

Question 6

In the context of SDN, which API is used between the SDN controller and the network devices to configure forwarding behavior?

Accepted Answer

Southbound API. Southbound APIs like OpenFlow, NETCONF, or gRPC communicate from controller to devices.

Answer

Northbound API

Answer

Eastbound API

Answer

REST API

Question 7

A network administrator is configuring a wireless network and wants to minimize interference. In the 2.4 GHz band, which set of channels are non-overlapping?

Accepted Answer

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

Answer

1, 5, 9, 13

Answer

1, 3, 5, 7, 9, 11

Answer

2, 7, 12

Question 8

During a TCP three-way handshake, which sequence of flags is sent from the client to initiate the connection?

Accepted Answer

SYN. The client sends a SYN segment to start the handshake.

Answer

SYN-ACK

Answer

ACK

Answer

FIN

Question 9

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 10

A developer is writing a Python script to interact with a REST API. The API requires a JSON payload to create a new resource. Which HTTP method should be used?

Accepted Answer

POST. POST is used to create a new resource on the server.

Answer

PATCH

Answer

PUT

Answer

GET

Question 11

Which DNS record type is used to verify domain ownership for email security protocols like SPF and DKIM?

Accepted Answer

TXT. SPF and DKIM records are stored as TXT records in DNS. SPF records specify which mail servers are authorized to send email for a domain, while DKIM records contain a public key used to verify email signatures. Both are implemented via TXT records, not other record types.

Answer

CNAME

Answer

MX

Answer

NS

Question 12

Which layer of the OSI model uses MAC addresses to deliver frames within the same network segment?

Accepted Answer

Layer 2 (Data Link). Layer 2 (Data Link) uses MAC addresses for local delivery.

Answer

Layer 1 (Physical)

Answer

Layer 3 (Network)

Answer

Layer 4 (Transport)

Question 13

Which TWO of the following are characteristics of UDP compared to TCP? (Select two.)

Accepted Answer

Lower overhead. UDP is connectionless and has lower overhead, but is unreliable.

Answer

Ordered data delivery

Answer

Reliable delivery with retransmission

Answer

Connection-oriented communication

Question 14

Which THREE of the following are true about HTTP/2 compared to HTTP/1.1? (Select three.)

Accepted Answer

Header compression using HPACK. HTTP/2 is binary, multiplexes streams, and uses HPACK for header compression.

Answer

Text-based protocol

Answer

Requires TLS/SSL encryption

Question 15

Which TWO of the following are valid private IPv4 address ranges? (Select two.)

Accepted Answer

10.0.0.0/8. RFC 1918 defines 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16.

Answer

172.15.0.0/12

Answer

172.32.0.0/12

Answer

169.254.0.0/16

Question 16

An engineer is troubleshooting a connectivity issue between two devices on different VLANs. The switch connecting the devices is configured with 802.1Q trunking. At which OSI layer do VLANs operate?

Accepted Answer

Layer 2. VLANs operate at Layer 2 (Data Link) because they segment broadcast domains based on MAC addresses and logical grouping, but they do not involve IP routing (Layer 3).

Answer

Layer 4

Answer

Layer 1

Answer

Layer 3

Question 17

A network application requires reliable, ordered delivery of data and uses a three-way handshake to establish a connection. Which transport protocol is being used?

Accepted Answer

TCP. TCP is a connection-oriented protocol that provides reliable, ordered delivery and uses a three-way handshake (SYN, SYN-ACK, ACK) to establish a connection.

Answer

UDP

Answer

ICMP

Answer

IP

Question 18

A network administrator needs to assign IP addresses to devices on a subnet with a /25 prefix. How many usable host addresses are available?

Accepted Answer

126. A /25 subnet has 7 bits for hosts (32-25=7), giving 2^7 = 128 total addresses, minus 2 (network and broadcast) = 126 usable hosts.

Answer

254

Answer

64

Answer

128

Question 19

A developer is building a real-time video streaming application that must minimize delay, even if some packets are lost. Which transport protocol is most appropriate, and why?

Accepted Answer

UDP, because it has lower overhead and no retransmission delay.. UDP is suitable for real-time streaming because it is connectionless and does not retransmit lost packets, reducing latency. TCP's retransmission and ordering would cause delays.

Answer

TCP, because it provides flow control to avoid congestion.

Answer

UDP, because it guarantees packet delivery.

Answer

TCP, because it ensures all packets arrive in order.

Question 20

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

Accepted Answer

AAAA. The AAAA (quad-A) record is the DNS resource record type defined in RFC 3596 to map a fully qualified domain name to a 128-bit IPv6 address. Unlike the A record, which stores a 32-bit IPv4 address, the AAAA record holds the longer IPv6 address, enabling clients to resolve hostnames to IPv6 destinations.

Answer

A

Answer

CNAME

Answer

MX