200-901 Network Fundamentals Practice Test 10 — 15 Questions

Question 1

A network engineer is using a REST API to retrieve a list of network devices from a controller. The API requires authentication using a token. Which HTTP header should be used to include the token in the request?

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

Authorization. For token-based authentication in REST APIs, the token is sent in the Authorization header, typically using the Bearer scheme. This header is designed to carry credentials and is processed by the server to validate the client's identity. Other headers like Content-Type and Accept serve different purposes and do not authenticate the request.

Answer

Accept

Answer

Content-Type

Answer

User-Agent

Question 2

A developer runs `python -c "import requests; r=requests.get('https://api.example.com/v1/status'); print(r.json())"` on a Linux host. The command returns a JSON payload instantly, but when the same request is sent to `http://api.example.com/v1/status` the client hangs and later times out with no response. Which network-layer behavior best explains why the HTTPS URL succeeds while the HTTP URL fails?

Accepted Answer

TCP port 80 is filtered by an intermediate device, while TCP port 443 is permitted.. The only difference between the two attempts is the destination port: 443 succeeds and 80 times out. When a TCP connection times out rather than receiving an immediate RST, an intermediate firewall or ACL is silently discarding the SYN. Because the hostname resolved and the encrypted session completed, name resolution and routing are functioning, leaving port-level filtering as the cause.

Answer

HTTP/1.1 requires a three-way handshake that TCP port 443 avoids by using UDP.

Answer

The server's default gateway is missing, so replies to port 80 are dropped.

Answer

The DNS A record for api.example.com resolves only for TLS connections.

Question 3

A network engineer is analyzing a packet capture and observes that a host sends a TCP segment with the SYN flag set, then receives a segment with both SYN and ACK flags set, and finally sends a segment with only the ACK flag set. Which TCP mechanism is being demonstrated?

Accepted Answer

TCP three-way handshake. The three segments with SYN, SYN-ACK, and ACK flags are the definitive signature of the TCP three-way handshake. This process synchronizes sequence numbers and establishes a reliable connection before data transfer begins. Other TCP mechanisms such as termination, window scaling, or selective acknowledgment involve different flags or options and occur at different stages.

Answer

TCP window scaling negotiation

Answer

TCP connection termination

Answer

TCP selective acknowledgment

Question 4

A developer is writing a script to interact with a REST API. The API documentation states that the base URL is https://api.example.com/v1/ and that the resource for users is /users. The developer needs to retrieve a list of all users. Which HTTP request should the developer send to the correct endpoint?

Accepted Answer

GET https://api.example.com/v1/users. RESTful APIs use HTTP methods semantically: GET for retrieval, POST for creation, PUT for update, DELETE for removal. To list users, a GET request to the users collection endpoint is correct. The base URL and resource path must be concatenated properly, and the plural form /users indicates the collection. The other methods would cause unintended actions or target the wrong resource.

Answer

PUT https://api.example.com/v1/users

Answer

GET https://api.example.com/v1/user

Answer

POST https://api.example.com/v1/users

Question 5

A network engineer is analyzing a packet capture and notices that a TCP session between a client and server is experiencing performance issues. The capture shows that the client sends a segment with the Push (PSH) flag set, but the server's acknowledgment does not immediately follow; instead, the server waits and sends a single acknowledgment for multiple segments. Which TCP mechanism is the server using to optimize network efficiency?

Accepted Answer

TCP delayed acknowledgment. The server is using delayed acknowledgment, a TCP feature where the receiver delays sending an ACK to potentially combine acknowledgments for multiple segments, reducing overhead. This is distinct from congestion control or window management mechanisms. The behavior described—waiting and then sending a single ACK for multiple segments—is characteristic of delayed ACK, which is commonly enabled by default in many TCP stacks.

Answer

TCP slow start

Answer

TCP selective acknowledgment (SACK)

Answer

TCP window scaling

Question 6

A developer is writing a Python script that will call a REST API. The API documentation states that the service listens on TCP port 443 and requires an encrypted channel. The developer wants to confirm from the command line that the remote host is reachable on that specific port before writing any code. Which command best accomplishes this?

Accepted Answer

nc -vz api.example.com 443. Testing a specific TCP port requires a tool that performs a TCP handshake against that port. Netcat's verbose zero-I/O scan does exactly that, confirming the API's listener is reachable before the developer invests time in code. Ping, traceroute, and nslookup validate different layers and cannot prove the service port is open.

Answer

nslookup api.example.com

Answer

traceroute api.example.com

Answer

ping api.example.com

Question 7

A network automation engineer is using the NETCONF protocol to configure a Cisco IOS XE device. The engineer sends an RPC with a candidate datastore, but the configuration does not take effect until a operation is performed. Which NETCONF capability must be supported by the device to allow this workflow?

Accepted Answer

urn:ietf:params:netconf:capability:candidate:1.0. The candidate datastore capability enables a two-step configuration process where changes are made to a candidate datastore and then applied to the running datastore via a commit. This is exactly the workflow described. The other capabilities provide additional features like confirmed commit, direct running edits, or error rollback, but they are not the fundamental requirement for using a candidate datastore.

Answer

urn:ietf:params:netconf:capability:rollback-on-error:1.0

Answer

urn:ietf:params:netconf:capability:confirmed-commit:1.0

Answer

urn:ietf:params:netconf:capability:writable-running:1.0

Question 8

A developer is building a Python application that must discover the IP address of a service registered in DNS. The application needs to resolve a domain name to an IPv4 address. Which DNS record type should the application query?

Accepted Answer

A. To resolve a domain name to an IPv4 address, the correct DNS record type is A. AAAA records are for IPv6, CNAME records provide aliases, and PTR records are for reverse lookups. The application needs forward resolution to an IPv4 address, which is exactly what an A record provides.

Answer

AAAA

Answer

CNAME

Answer

PTR

Question 9

A network engineer is troubleshooting a connectivity issue between two hosts on different subnets. The engineer suspects a problem with the default gateway configuration. Which two statements about default gateways are correct? (Choose two.)

Accepted Answer

The default gateway is used to forward packets destined for remote networks.. The default gateway must be on the same subnet as the host so that the host can reach it via ARP. It is used to forward packets destined for remote networks. Layer 3 switches can act as gateways, and multiple gateways require redundancy protocols for automatic failover. The gateway is not limited to DNS traffic.

Answer

The default gateway is only used for DNS resolution.

Answer

A host can have multiple default gateways configured for redundancy without any additional protocols.

Answer

The default gateway must be a router; a Layer 3 switch cannot serve as a default gateway.

Question 10

A network automation engineer must ensure that a Python script running on a management workstation can resolve internal service names such as `inventory.corp.local` and `billing.corp.local`. The workstation currently resolves public names correctly but fails on the internal ones. The engineer inspects `/etc/resolv.conf` and sees a single `nameserver 8.8.8.8` entry. Which change most directly resolves the problem?

Accepted Answer

Add a `search corp.local` line and point the nameserver at the internal DNS server.. The workstation is pointing at a public recursive resolver that has no authority over the private corp.local zone, so internal names return no answer. Pointing the client at the corporate DNS server that hosts the zone, plus adding the search domain for short-name expansion, restores resolution for all internal services rather than a hand-picked few.

Answer

Increase the DNS timeout value so the public resolver has more time to answer.

Answer

Enable DNSSEC validation on the workstation's resolver library.

Answer

Add static entries for both service names to the local hosts file.

Question 11

A developer is using a REST API to retrieve data from a network controller. The API requires the client to include an API key in the HTTP request header for authentication. Which HTTP header is typically used to carry the API key?

Accepted Answer

Authorization. The Authorization header is the standard HTTP header for transmitting authentication credentials. API keys are commonly placed in this header, often with a prefix like Bearer. Other headers like Content-Type, Accept, and User-Agent serve different purposes such as content negotiation or client identification, and are not used for authentication.

Answer

User-Agent

Answer

Content-Type

Answer

Accept

Question 12

An engineer is comparing TCP and UDP for a new telemetry service that sends small, frequent datagrams from thousands of IoT sensors to a collector. The design prioritizes low overhead and does not require retransmission of lost readings. Which two characteristics apply to UDP in this scenario? (Choose two.)

Accepted Answer

It provides no delivery guarantee, so lost datagrams are simply not retransmitted.. UDP's value in high-volume telemetry is its minimal overhead and connectionless, best-effort model. The small fixed header reduces cost per datagram, and the absence of acknowledgments and retransmissions means lost readings are simply dropped, which the design accepts. Ordering, reliability, and congestion control are all absent and would have to be added at the application layer if required.

Answer

It guarantees in-order delivery of datagrams to the application.

Answer

It performs a three-way handshake before data transmission to establish state.

Answer

It automatically adjusts its congestion window in response to network loss.

Question 13

A network engineer is troubleshooting an issue where a client cannot reach a web server at 203.0.113.10. The engineer runs a traceroute from the client and sees that the path stops at a router with IP 198.51.100.1, which is the last hop before the destination. The engineer suspects that the router is dropping packets due to an ACL. Which command should the engineer use on the router to verify if an ACL is blocking traffic to the web server?

Accepted Answer

show ip access-lists. To verify if an ACL is blocking traffic, the engineer should examine the ACL configuration and match counters. The show ip access-lists command provides this information, allowing the engineer to see if a deny entry is matching the traffic in question. Other commands like show ip route or show ip interface do not show ACL contents, and debug ip packet is too disruptive for routine troubleshooting.

Answer

show ip interface

Answer

show ip route 203.0.113.10

Answer

debug ip packet

Question 14

A developer's application opens a TCP connection to a REST API, sends a request, and receives a response. The developer then wants to reuse the same connection for several subsequent requests to the same host instead of opening a new socket each time. Which HTTP behavior makes this reuse possible?

Accepted Answer

Persistent connections keep the TCP socket open for multiple request/response exchanges.. Persistent connections, the default in HTTP/1.1, let a client send multiple requests over one TCP socket. This avoids re-establishing the connection and re-entering TCP slow start for every call, which is the reuse the developer wants. Cookies, protocol upgrades, and HTTP/1.0 behavior do not provide this transport-level efficiency.

Answer

The server sends a 101 Switching Protocols response to upgrade the socket.

Answer

The client multiplexes requests by interleaving them in a single HTTP/1.0 stream.

Answer

HTTP cookies are exchanged so the server can correlate successive sockets.

Question 15

A developer is writing a Python script that uses the requests library to interact with a REST API. The script must handle common HTTP status codes appropriately. Which two actions should the developer take to ensure robust error handling? (Choose two.)

Accepted Answer

Check the response.status_code attribute and branch logic based on the code.. To robustly handle HTTP errors, the developer should check the status code and branch logic accordingly, and use raise_for_status() to raise exceptions for 4xx and 5xx responses. These practices allow the script to respond appropriately to different error conditions, such as retrying or logging. Other options either introduce risks or do not address error handling effectively.

Answer

Always assume the response is JSON and parse it without checking the Content-Type header.

Answer

Disable SSL verification to avoid certificate errors.

Answer

Set the timeout parameter to a very high value to avoid connection errors.