Unit 6: Application layer - Practice Quiz

1 What is the main function of the Domain Name System (DNS)?

2 Which DNS record type maps a domain name to an IPv4 address?

3 What does DHCP commonly provide to a client device?

4 What is the first message normally sent by a DHCP client seeking network configuration?

5 Which protocol is commonly used to send system log messages to a remote server?

6 What is TELNET primarily used for?

7 Which protocol is primarily used to send electronic mail between mail servers?

8 Which protocol commonly downloads email messages from a mail server to a client?

9 What does FTP stand for?

10 Which protocol provides encrypted file transfer through an SSH connection?

11 What does WWW stand for?

12 What is the primary purpose of HTTP?

13 Which HTTP method is commonly used to retrieve a resource from a server?

14 What is SNMP mainly used for?

15 What does an SNMP manager communicate with on a managed device?

16 What security service is provided by IPSec?

17 What does VPN stand for?

18 What is a common purpose of a VPN?

19 What is the main purpose of a network firewall?

20 Which information can a basic packet-filtering firewall examine?

21 A DNS resolver has cached an address record with a TTL of 600 seconds. After 400 seconds, the authoritative server changes the address. What will normally happen when the resolver receives another query for the name?

22 An administrator wants email addressed to user@example.com to be delivered to mail.example.net. Which DNS record should be configured for example.com?

23 A DHCP server and a new client are located on different IP subnets separated by a router. What is needed if the server must assign an address to the client?

24 A DHCP client reaches the normal renewal time for its current lease and can still contact the server that issued it. Which message does the client send first to renew the lease?

25 Logs from several routers reach a central logging server, but their timestamps cannot be reliably compared. Which change most directly addresses the problem?

26 An administrator captures traffic from a TELNET management session. Which security issue is most likely?

27 A user wants messages and folders to remain synchronized across a laptop and a phone while mail stays on the server. Which protocol is most appropriate for retrieving the mail?

28 An email client must send a binary image as an attachment through a traditional text-oriented email system. Which mechanism enables this?

29 An FTP client is behind a firewall that blocks unsolicited inbound connections. Which FTP mode is generally easier to use in this situation?

30 A diskless device must download a small boot configuration from a local server with minimal protocol overhead and no user authentication. Which protocol best matches the requirement?

31 A page at https://example.com/docs/index.html contains the relative link images/logo.png. Which resource does a browser request when the link is selected?

32 A browser sends a conditional GET with If-None-Match, and the server determines that the cached representation is still current. Which response is most appropriate?

33 A web page requires many resources from the same server. What is the main benefit of using persistent HTTP connections?

34 A network manager must be notified immediately when a router interface goes down, rather than repeatedly checking the interface state. Which SNMP mechanism should be used?

35 A monitoring application needs to retrieve a specific interface counter from an SNMP agent. How is that managed value uniquely identified?

36 A company connects two office networks across the Internet using security gateways. It wants the original IP packets, including their headers, protected inside new packets. Which IPSec configuration is appropriate?

37 IPSec traffic must cross a NAT device that changes IP addresses. Why is ESP with NAT traversal generally preferred over AH?

38 Two branch offices need their internal subnets to communicate securely over the public Internet without employees starting individual VPN sessions. Which design is most appropriate?

39 A firewall allows an internal host to initiate a TCP connection to a web server and automatically permits only the matching return traffic. What capability is being used?

40 A public web server must be reachable from the Internet, but it should not be placed directly inside the private employee network. Where should it be located?

41 An authoritative DNS server returns an NXDOMAIN response containing an SOA record whose RR TTL is 3600 seconds and whose MINIMUM field is 600 seconds. Under negative-caching rules, what maximum initial TTL should a recursive resolver assign to this negative answer?

42 A .com server delegates example.com to ns1.example.com and ns.provider.net, including A records for both names in the Additional section. How should a security-conscious recursive resolver treat these addresses?

43 A zone replaces an A RRset, but the old RRset's RRSIG remains cryptographically valid for another hour. An attacker replays the correctly signed old response to a validating resolver. Which statement best describes DNSSEC's behavior?

44 A DHCP relay forwards a DHCPDISCOVER with giaddr = 10.20.0.1 and ciaddr = 0.0.0.0. What is the primary significance of giaddr to the DHCP server?

45 A DHCP client has a valid lease but receives no response from its original server at renewal time . When rebinding time is reached, what should the client do?

46 A syslog message begins with the priority field <165>. Using , how should this priority be decoded?

47 A TELNET application must transmit a literal data byte 0xFF, which is also the Interpret As Command (IAC) byte. Which byte sequence must it place in the TELNET data stream?

48 An SMTP receiver commits a message to durable storage and sends 250 OK after the terminating <CRLF>.<CRLF>, but the TCP connection fails before the sender receives that reply. What outcome is consistent with SMTP semantics?

49 A message with From: user@example.com is forwarded without modifying its DKIM-signed headers or body. The final receiver finds that SPF fails because the forwarder's IP is unauthorized, but an example.com DKIM signature validates. Under DMARC, what is the likely result?

50 An FTP server behind NAT responds to PASV with a private IP address and a port number, causing the client's data connection to fail. Which change most directly avoids reliance on the advertised private address?

51 A document is loaded from https://shop.example:443/a/page.html. Which resource has the same origin as the document under the Web's scheme-host-port origin model?

52 A client sends a GET request with If-None-Match: "v2" and an If-Modified-Since date older than the resource's last modification. The current representation has ETag "v2". Assuming ordinary HTTP conditional-request processing, what should the origin server return?

53 Multiple HTTP/2 streams share one TCP connection. A TCP segment containing data for one stream is lost while later segments contain frames for other streams. What is the expected transport-level effect?

54 An SNMP GETBULK request contains five variable bindings, with non-repeaters = 2 and max-repetitions = 4. Assuming no size truncation or early end-of-MIB condition, how many variable bindings can the response contain?

55 An SNMP Counter32 is sampled as 4,294,967,290 and later as 7. Assuming exactly one wrap and no reset, how many events occurred between samples?

56 Two security gateways must protect entire internal IP packets while preventing observers on the public network from learning internal source and destination addresses. Which IPsec arrangement meets this requirement?

57 An IPsec Security Association uses a 64-packet anti-replay window. The highest authenticated sequence number is 1050. Which arriving packet can be accepted, assuming sequence number 990 has not previously arrived and sequence number 1040 has?

58 A remote-access VPN installs an IPv4 default route through the tunnel but leaves the client's native IPv6 configuration unchanged. The client accesses a dual-stack website over IPv6. What security issue is most likely?

59 A TCP connection's outbound SYN passes through stateful firewall A, but routing changes cause the returning SYN-ACK to pass through stateful firewall B. Firewall B has no synchronized state table. What is the most likely result?

60 A firewall and an internal host apply different rules when reassembling overlapping IPv4 fragments. An attacker crafts overlaps so the firewall sees an allowed transport header while the host reconstructs a prohibited one. Which defense most directly addresses this evasion?