200-901 Network Fundamentals Practice Test 3 — 15 Questions

Question 1

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. The southbound API is the interface between the SDN controller and the underlying network devices (switches, routers), used to program forwarding tables and configure behavior. Protocols like OpenFlow, NETCONF, and P4 are typical southbound interfaces. The controller translates northbound application intent into southbound device instructions.

Answer

Northbound API

Answer

Eastbound API

Answer

REST API

Question 2

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. In the 2.4 GHz ISM band, the available channels are spaced 5 MHz apart, but each Wi-Fi channel is 20 MHz wide, so adjacent channels overlap. Only channels 1, 6, and 11 are spaced far enough apart (25 MHz between centers) to avoid overlapping in North America, making them the standard non-overlapping set. Using these three channels allows multiple access points to operate in close proximity with minimal co-channel interference.

Answer

1, 5, 9, 13

Answer

1, 3, 5, 7, 9, 11

Answer

2, 7, 12

Question 3

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 4

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 correct because the HTTP POST method is used to create a new resource on the server, with the resource representation sent in the request body as JSON. POST is neither safe nor idempotent, meaning repeated identical requests may create multiple resources. This matches the requirement to create a new resource via a REST API.

Answer

PATCH

Answer

PUT

Answer

GET

Question 5

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 6

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 7

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

Accepted Answer

Lower overhead. Option D (Lower overhead) is correct because UDP has a fixed 8-byte header containing only source port, destination port, length, and checksum, with no sequence/acknowledgment fields, handshake, or connection state, whereas TCP's 20-byte (or larger) header and connection tracking add significant overhead. Option E (No flow control or congestion control) is correct because UDP simply sends datagrams without windowing, slow-start, or congestion-avoidance algorithms, so it does not throttle the sender based on receiver capacity or network congestion. Options A, B, and C are TCP characteristics: TCP provides ordered delivery via sequence numbers, reliable delivery with acknowledgments and retransmission, and connection-oriented communication via the three-way handshake, none of which UDP offers.

Answer

Ordered data delivery

Answer

Reliable delivery with retransmission

Answer

Connection-oriented communication

Question 8

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

Accepted Answer

Header compression using HPACK. Option C is correct because HTTP/2 introduces HPACK (RFC 7541), a header compression scheme that uses static and dynamic tables plus Huffman encoding to shrink repetitive header fields, which HTTP/1.1 sends uncompressed as plain text on every request. Option D is correct because HTTP/2 adds server push, allowing the server to proactively send resources (e.g., via PUSH_PROMISE frames) that the client will likely need, a feature absent from HTTP/1.1. Option E is correct because HTTP/2 multiplexes many concurrent streams over one TCP connection using binary framing, eliminating HTTP/1.1's head-of-line blocking at the request level and its need for multiple parallel connections. Option A is wrong because HTTP/2 is a binary protocol, whereas HTTP/1.1 is text-based. Option B is wrong because HTTP/2 does not mandate TLS; it can run over cleartext TCP (h2c), although browsers only implement it over TLS.

Answer

Text-based protocol

Answer

Requires TLS/SSL encryption

Question 9

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

Accepted Answer

10.0.0.0/8. Option B, 10.0.0.0/8, is correct because RFC 1918 designates the entire 10.0.0.0/8 block as a private IPv4 range, giving roughly 16.7 million addresses for internal use. Option E, 192.168.0.0/16, is also correct because RFC 1918 reserves 192.168.0.0/16 for private networks, commonly used in home and small-office LANs. The third RFC 1918 range, 172.16.0.0/12, covers 172.16.0.0 through 172.31.255.255, which is why option A (172.15.0.0/12) and option C (172.32.0.0/12) fall outside the private block and are invalid. Option D, 169.254.0.0/16, is not a private range but the APIPA/link-local block (RFC 3927), automatically self-assigned when DHCP fails, so it does not qualify.

Answer

172.15.0.0/12

Answer

172.32.0.0/12

Answer

169.254.0.0/16

Question 10

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 (the Data Link layer) of the OSI model because they segment a single physical switch into multiple logical broadcast domains using 802.1Q tags inserted into Ethernet frames. The 802.1Q tag adds a 12-bit VLAN ID field to the Ethernet frame header, which is a Layer 2 construct. Routing between VLANs requires a Layer 3 device (router or Layer 3 switch), but the VLAN membership and tagging itself is strictly a Layer 2 function.

Answer

Layer 4

Answer

Layer 1

Answer

Layer 3

Question 11

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 12

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 13

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 the correct choice because it has minimal overhead (8-byte header vs TCP's 20+ bytes), no handshake, and no retransmission logic, so lost packets do not stall the stream. For real-time video, a late packet is worse than a lost one, so UDP's fire-and-forget model minimizes delay. Application-layer protocols like RTP/WebRTC build on UDP to handle ordering and loss recovery selectively.

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 14

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

Question 15

An organization has a web server that needs to be reachable via both 'www.example.com' and 'example.com'. Which DNS record type should be used to make 'example.com' an alias for 'www.example.com'?

Accepted Answer

CNAME record. A CNAME record creates an alias that points to the canonical name. The A record points to an IP address, not another domain.

Answer

A record

Answer

MX record

Answer

NS record