CCNA Network Services and Security Questions

The order of ACL entries is crucial; the first match is applied. Here, the permit any any matches all SMTP before the deny can block the specific traffic.

The deny any any matches all SMTP, so the subsequent permit for the specific source/destination is never reached.

The permit ip any any matches all traffic, so the subsequent deny for SMTP is never applied.

Incorrect because the dns-server statement is optional; its absence does not prevent the DHCP server from assigning IP addresses to clients.

Incorrect because the ip helper-address command is only necessary when forwarding DHCP requests across subnets, not when the router itself is the DHCP server on the VLAN.

This option is incorrect because sticky learning does not remove or disable the configured maximum secure MAC address limit; the limit remains enforced regardless of sticky learning.

This option is incorrect because sticky learning does not change the port type or convert it into a trunk; port mode remains unchanged and unrelated to sticky MAC learning.

This option is incorrect because sticky MAC addresses can persist if the configuration is saved, so port security is not disabled after a reboot; sticky learning supports persistence, not disabling.

Option A is incorrect because the RADIUS server does not handle Layer 2 trunk negotiation. Trunking is managed by protocols such as DTP or manual switchport configuration, not by the authentication server.

Option C is incorrect because DHCP is responsible for IP address assignment, not the RADIUS server. RADIUS focuses solely on authentication, authorization, and accounting functions.

Option D is incorrect because the RADIUS server does not generate ARP replies or perform any gateway functions. These tasks are handled by routers or Layer 3 devices in the network.

The ACL is applied outbound on G0/0 instead of inbound on G0/1. Although it may achieve the goal, it is not the most efficient placement and may not be the expected answer in a PBQ.

Missing the explicit deny statement. The implicit deny at the end of the ACL will block other traffic, but the question expects an explicit deny for clarity and completeness.

The deny statement is too broad; it denies all IP traffic, not just traffic to the loopback. The correct deny should be specific to the loopback host.

In restrict mode, the port does not go to err-disabled state; that behavior is specific to shutdown mode. Shutdown mode disables the port upon a violation, whereas restrict mode only drops traffic from unknown MACs and increments the violation counter.

Port security does not automatically learn additional MAC addresses after a delay; it strictly enforces the configured maximum number of MAC addresses. If the maximum is set to 2, any new MAC address beyond that triggers a violation action (restrict, shutdown, or protect) immediately, not after 30 seconds.

STP (Spanning Tree Protocol) is used to prevent loops in redundant topologies and does not enforce port security. Port security violations are handled by the port security feature itself, independent of STP. STP blocking a port would be unrelated to MAC address limits.

Candidates think that seeing the same global port means overload is not operating, but port reuse is normal in extended PAT.

Candidates may misinterpret the summary line as a static identity NAT rule that locks all translations to a single port.

Candidates confuse pool exhaustion (no free global addresses) with port reuse. Exhaustion typically manifests as translation failures, not as many entries sharing the same port.

Incorrect. HTTPS uses TCP, not UDP. Denying UDP port 443 would not block HTTPS traffic, so this option is factually wrong.

Incorrect. It is unnecessary to deny all IP traffic to block HTTPS. Targeting the specific TCP port 443 is sufficient and more secure practice.

Incorrect. ACLs can filter by destination port even when using the host keyword. Both host-based IP matching and port filtering are valid in extended ACLs.

STP root bridge priority is irrelevant here because the network path to the IP address is already functional, meaning Layer 2 switching and spanning-tree topology are stable and not causing the failure.

PPP encapsulation on the WAN edge is not the cause since the symptom is specific to hostname resolution failure, and IP connectivity over the WAN is already confirmed as working.

EtherChannel member consistency issues would affect link aggregation and potentially cause connectivity failures, but since the client can reach the service by IP, EtherChannel problems are not the root cause.

Incorrect because ACLs do not evaluate every line; they stop processing once a match is found, making this statement false.

Incorrect because Cisco ACLs do not end with an implicit permit; the default behavior is an implicit deny for unmatched traffic.

Incorrect because ACLs filter traffic at Layer 3 and Layer 4, not at Layer 1, so this statement is factually wrong.

Re-authentication forces the phone to re-authenticate, but the port remains in single-host mode, which only allows one authenticated device. The phone's data and voice domains are not separated, so the voice VLAN assignment still fails.

The voice VLAN is already configured with 'switchport voice vlan 10' as stated in the scenario. The issue is not the VLAN definition but the authentication domain separation; the phone remains unauthenticated because the port cannot assign the voice VLAN without proper multi-domain support.

Setting 'authentication port-control force-authorized' bypasses 802.1X authentication entirely, which defeats the purpose of port-based security. It would allow the phone to connect without authentication, but the voice VLAN assignment still requires proper domain handling; moreover, this is not a secure solution.

This option is incorrect because Syslog does not assign IP addresses; DHCP is the protocol responsible for IP address allocation in Cisco networks.

This option is incorrect because Syslog does not prevent switching loops; this function is handled by Spanning Tree Protocol (STP).

This option is incorrect because Syslog complements but does not replace broader network monitoring systems that provide additional analysis and alerting capabilities.

The 2-WAY state confirms bidirectional communication between OSPF neighbors but does not indicate that the full link-state database has been exchanged. It is an intermediate step before full adjacency.

EXSTART is the initial phase of database exchange where routers negotiate master-slave roles and sequence numbers. It does not mean the databases are fully synchronized yet.

INIT state means a router has received a hello packet from a neighbor but has not confirmed bidirectional communication, so full database exchange has not started.

The ACL does not block all traffic; it only denies TCP traffic destined for port 80 (HTTP). Other traffic, including ICMP, is permitted by the subsequent 'permit ip any any' statement.

Line 20 does not override line 10 because ACLs use first-match logic. Once a packet matches line 10 (TCP port 80), it is denied and no further processing occurs. Line 20 only applies to packets that do not match earlier entries.

ICMP is not explicitly blocked; it is permitted by the 'permit ip any any' statement on line 20, which covers all IP protocols including ICMP. The user's ping works, confirming this.

This is incorrect because tagged traffic on the trunk is not dropped due to a native VLAN mismatch; tagged frames continue to be forwarded normally if VLANs are allowed on both sides.

This option is wrong since a native VLAN mismatch does not disable Spanning Tree Protocol; STP continues to operate normally on the trunk link.

This is incorrect because Cisco switches do not automatically convert a trunk port to an access port due to a native VLAN mismatch; the trunk remains active.

The specific factual error: The inside/outside interface roles are reversed; PAT is applied to the wrong interface.

The specific factual error: The ACL does not match the inside network, so PAT will not be applied to LAN traffic.

The specific factual error: The PAT command uses the wrong ACL number; it should use ACL 1, not ACL 2.

The symptom described is that external hosts cannot initiate connections to internal hosts. Even if the NAT pool were exhausted, internal hosts would still be able to initiate outbound connections (using PAT if configured), and external hosts would still be unable to initiate inbound connections unless static NAT or port forwarding is configured. Pool exhaustion would cause outbound failures, not specifically inbound failures.

The inside local addresses (192.168.1.x) are private IPs that are typically configured on the inside interface. The NAT translations show them mapping to public IPs, indicating that the router is correctly performing NAT. Asymmetric routing would cause connectivity issues in both directions, not just inbound, and is not indicated by the given symptoms.

The question states that internal hosts can ping external servers, which means return traffic is reaching the internal hosts. If the outside global addresses were not routable, the ping would fail because the external server would not be able to send a reply. Therefore, the addresses must be routable in this scenario.

PortFast is a spanning-tree optimization that speeds up the transition of an access port to forwarding; it does not control which sources can initiate SSH.

Disabling logging prevents the router from recording events, but it does not prevent unauthorized subnets from attempting SSH access.

Replacing SSH with Telnet does not add source filtering and actually reduces security; Telnet transmits credentials in clear text.

Incorrect because changing the MAC address does not affect DNS or hostname resolution. MAC addresses operate at Layer 2 and are unrelated to IP services like DNS.

Incorrect because a trunk native VLAN setting relates to VLAN tagging on switches and does not impact a host’s ability to resolve hostnames or DNS functionality.

Incorrect because OSPF router ID is a routing protocol parameter used by routers and does not influence DNS or hostname resolution on end hosts.

The command 'show ip nat statistics' provides summary statistics such as total translations, hits, misses, and expired translations, but it does not list the actual translation entries. To view active translations, you must use 'show ip nat translations'.

The command 'show ip interface brief' displays the status and IP addresses of interfaces, but it does not show NAT translations. To verify static NAT, you should use 'show ip nat translations' or 'show ip nat statistics' to confirm the mapping is active.

Root Guard prevents a port from becoming a root port by blocking superior BPDUs but does not err-disable or shut down the port upon receiving BPDUs. It is designed to maintain root bridge stability rather than protect edge ports from unauthorized switches.

Loop Guard protects against loops caused by unidirectional link failures by preventing ports from transitioning to forwarding state when BPDUs are missing. It does not err-disable ports upon receiving BPDUs and therefore does not cause the port shutdown described.

Storm Control monitors traffic levels to prevent broadcast, multicast, or unicast storms by blocking traffic when thresholds are exceeded. It does not react to BPDUs or cause ports to shut down upon BPDU reception, so it is unrelated to the described behavior.

Syslog is designed to send event messages and system logs, not detailed traffic flow summaries. It cannot provide source and destination IP addresses with byte counts, so it is incorrect for this question.

SNMP traps are notifications about specific device events or threshold conditions, not detailed records of traffic conversations. They do not include flow metadata like source/destination IP and byte counts, making this option incorrect.

NTP is used solely for synchronizing time across network devices and does not provide any traffic metadata or flow information, so it is not the correct feature in this context.

The specific factual error: The shared key is used for encrypting RADIUS traffic, but server reachability is confirmed; the key mismatch would cause authentication failures, not port unauthorized state due to missing fallback.

The specific factual error: The question states the server uses UDP port 1812, which is correct. The switch would need explicit configuration to use 1645; default is 1812.

The specific factual error: Privilege level is not required for authentication; it affects authorization. The local user exists and can authenticate, so SSH fallback is fine.

PortFast is a Spanning Tree Protocol feature that immediately transitions a port to forwarding state, bypassing listening and learning states. It does not perform any validation of ARP packets or prevent IP-to-MAC spoofing attacks.

EtherChannel is a link aggregation technology that combines multiple physical links into a single logical link to increase bandwidth and provide redundancy. It does not inspect or validate ARP packets, so it cannot prevent IP-to-MAC spoofing.

NetFlow is a network monitoring protocol that collects IP traffic statistics for analysis and troubleshooting. It provides visibility into traffic patterns but does not actively block or validate ARP packets, so it cannot prevent spoofing attacks.

Option A incorrectly states that restrict mode always causes the port to shut down. In reality, restrict mode blocks unauthorized traffic but keeps the interface up. Shutdown mode is the one that disables the port and causes an error-disabled state, which contradicts the scenario where the port remains up/up.

Option C is incorrect because sticky MAC addresses are not automatically replaced when a new device connects. Instead, the switch enforces the violation action when an unauthorized MAC address appears, rather than overwriting the existing sticky entries.

Option D is false because port security controls all user data traffic on access ports by filtering frames based on source MAC addresses. It is not limited to management traffic, so this option misrepresents the scope of port security.

A MAC address is a hardware identifier used for local network communication at Layer 2, and it has no role in hostname resolution. Changing the MAC address would not affect the ability to resolve hostnames to IP addresses.

A trunk native VLAN is a configuration for switch ports that carry multiple VLANs, and it is unrelated to hostname resolution. The symptom described is a DNS issue, not a VLAN or trunking problem.

OSPF router IDs are used by routers in OSPF routing protocol operations, not by end hosts. End hosts do not participate in OSPF and do not require a router ID for any function, including name resolution.

Candidates often jump to switch security features when they see DHCP issues, but without evidence of a switch misconfiguration, it is not the most direct next action.

Test-takers often consider firewalls as universal blockers, forgetting that in a flat Layer 2 domain, broadcast traffic such as DHCP Discover is not filtered by a firewall.

Candidates prefer simple client-side fixes, but CCNA troubleshooting emphasises identifying root causes before applying band-aid solutions.

Incorrect because standard ACLs filter only by source IP address and cannot distinguish between different protocols or ports, making them insufficient for the requirement to allow HTTPS but deny Telnet.

Incorrect because a wildcard mask controls which bits of an IP address are matched but does not provide any capability to filter traffic based on protocol or port information, which is essential here.

Incorrect because wireless SSID ACLs relate to WLAN access control and do not filter IP traffic based on protocol or port, making them irrelevant to the question about IP traffic filtering.

This option denies UDP traffic on port 23, but Telnet uses TCP, not UDP. Therefore, this ACL entry will not block Telnet sessions and is incorrect.

This option denies TCP traffic destined to the 10.20.30.0/24 subnet on port 23, which blocks inbound Telnet sessions to the subnet but does not prevent users inside the subnet from initiating outbound Telnet sessions.

This option permits TCP traffic from the subnet to any destination on port 80 (HTTP), allowing web browsing but does not block Telnet traffic, so it does not meet the requirement.

A common misconception is that any dynamic NAT entry for the same inside local address takes precedence or conflicts with static entries. In reality, the more specific static mapping takes priority for matching traffic, and the dynamic entry handles unrelated flows.

Candidates may misinterpret the presence of the same inside local IP in two entries as a duplicate session. Asymmetric routing would require inconsistent state in both directions, but here the NAT table correctly tracks distinct flows.

Some candidates believe that a single inside address can only participate in one type of NAT at a time. In fact, multiple NAT rules can coexist, and the router will use the most specific match (static port mapping) before falling back to dynamic PAT for unmapped ports.

Standard ACLs can be applied near the destination or source, but the placement guidance for extended ACLs is based on their ability to filter on source and destination IP addresses and ports, not on limitations of standard ACLs. The reason for placing extended ACLs near the source is to filter traffic early, not because standard ACLs cannot be applied near the destination.

NAT translation is typically performed on routers or firewalls at network boundaries, and ACL placement for filtering is independent of NAT configuration. Placing an extended ACL near the source does not directly affect NAT translation; NAT uses its own rules and is not a factor in ACL placement decisions.

Extended ACLs can be applied inbound or outbound on any interface, not just inbound on access interfaces. The statement is factually incorrect; extended ACLs are versatile and can be placed in various locations depending on the filtering requirements.

Option A is incorrect because SNMPv3 supports both IPv4 and IPv6 networks. It is not limited to IPv4 only, so this option misrepresents SNMPv3’s capabilities.

Option C is incorrect since SNMPv3 continues to support monitoring functions such as interface counters. It does not remove or restrict these capabilities.

Option D is incorrect because SNMPv3 does not replace syslog. Both protocols coexist and serve different roles in network management and logging.

Application is not part of the AAA acronym and does not relate to the core security functions of Authentication, Authorization, or Accounting, making it an incorrect choice.

Accounting is the third A in AAA and focuses on logging user activities, not the second A which controls user permissions after authentication.

Auditing, while related to security, is not part of the AAA acronym and does not represent the second A in the AAA framework.

The specific factual error is that the inside and outside interfaces are swapped; G0/0 is the internal interface and must be 'ip nat inside'.

The specific factual error is that the ACL permits the wrong subnet (192.168.2.0 instead of 192.168.1.0).

The specific factual error is that both the interface directions are swapped and the ACL is changed, but the interface directions must be correct for NAT to work.

The specific factual error is that an unreachable DNS server must be removed or replaced to resolve external queries; simply fixing internal records does not address the timeout issue.

The specific factual error is that reverse DNS must match the forward record for consistency; an incorrect PTR record is a problem even if forward resolution works.

The specific factual error is that forward and reverse DNS are independent; adding a PTR record does not create an A record. The A record must exist for forward queries to succeed.

The err-disabled state is characteristic of the shutdown violation mode, not restrict. In restrict mode, the port remains up and only drops violating traffic while logging the event.

Port security does not change the port's operational mode; it only controls MAC address access. Converting a port to a trunk is unrelated to port security and requires explicit configuration.

Port security violation modes do not automatically change. The mode is statically configured and remains the same regardless of the number of violations. There is no automatic escalation from restrict to shutdown.

The network command in DHCP pool configuration requires a subnet mask in dotted decimal format, not CIDR notation like /24.

The lease command uses days as its unit; `lease 24` sets a 24-day lease, not the required 1 day.

The lease command sets duration in days, so `lease 24` gives a 24-day lease instead of a 1-day lease.

NAT overload translates private IP addresses to a public IP for outbound traffic but does not forward DHCP broadcasts between VLANs. It is unrelated to DHCP relay functionality required for inter-VLAN DHCP communication.

Port security restricts which MAC addresses can connect to a switch port but does not forward DHCP broadcasts or relay DHCP messages between VLANs, so it cannot enable DHCP communication across VLANs.

Private VLANs isolate devices within a VLAN for security purposes but do not provide DHCP relay capabilities or forward DHCP requests between VLANs, making this option incorrect.

Incorrect. Applying the ACL outbound on VTY lines does not control incoming management traffic. The correct direction for access control on VTY lines is inbound.

Incorrect. SSH uses TCP port 22, not UDP. Configuring ACLs to permit UDP port 22 will not allow SSH connections, making this option invalid.

Incorrect. The 'access-class' command works with both Telnet and SSH to restrict access based on IP addresses. It is not limited to Telnet only.

The 'ip dhcp excluded-address' command is used on a DHCP server to prevent certain addresses from being assigned, not on a router interface to forward DHCP requests. This command would not help clients in VLAN 40 reach the centralized DHCP server.

The 'service dhcp' command globally enables the DHCP server or relay agent on a Cisco device, but it does not specify where to forward requests. Without the 'ip helper-address' command, DHCP broadcasts will not be forwarded to the server.

The 'ip default-gateway' command is used on a switch to set a default gateway for management purposes, not to forward DHCP broadcasts. It does not provide DHCP relay functionality.

Standard IPv4 ACLs only filter traffic based on the source IP address and cannot filter by destination IP or TCP/UDP port numbers, making this option incorrect for the question's requirements.

Prefix lists are used primarily for route filtering in routing protocols and do not filter traffic based on Layer 4 port numbers or destination IP addresses, so this option is incorrect.

Native VLAN ACLs apply to traffic within a VLAN but do not provide the granular filtering capabilities involving source/destination IP and port numbers, so this option is not correct.

The specific factual error is that the pool address 203.0.113.2 and static mapping to 203.0.113.3 are valid and do not need changing.

The specific factual error is that PAT does not allow inbound connections initiated from outside; static NAT is required for that purpose.

The specific factual error is that the inside interface IP is part of the 192.168.1.0/24 network and should not be changed; the ACL should be adjusted instead.

The ACL used by NAT should match the inside local addresses that need to be translated, typically using a permit statement. If the ACL denies inside addresses, no traffic will be matched for translation, causing NAT to fail. The correct ACL should permit the inside network.

PAT (Port Address Translation) does not require DHCP on any interface. PAT translates multiple private IP addresses to a single public IP using different port numbers, and it works independently of how IP addresses are assigned. DHCP is only needed if the interface needs to obtain an IP address dynamically.

NAT overload (PAT) is independent of the routing protocol used. It works with static routes, OSPF, EIGRP, or any other routing protocol. The routing protocol only affects how packets are forwarded, not how NAT translates addresses.

Disabling DAI on all VLANs globally removes ARP spoofing protection network-wide, which is excessive and reduces security unnecessarily. The question requires a targeted fix, so this option is incorrect.

Trusting the user-facing printer access port for DHCP snooping and DAI is too permissive and can allow malicious ARP packets, weakening security. It is not recommended as a best practice or exam answer.

Changing the printer to use a larger MTU does not affect ARP packet validation or DAI behavior. MTU size is unrelated to ARP inspection, so this option is irrelevant and incorrect.

Candidates think any absence of dynamic entries is due to ACL mismatch, overlooking the prerequisite that the inside interface must be configured with ip nat inside for NAT to function at all.

The presence of static NAT translations in the output indicates that the ip nat outside command is already applied on the WAN interface.

Candidates may focus on the static entries, but the symptom is missing dynamic translations; bad static mappings would not prevent dynamic translations from appearing.

The access list is used to define which inside local addresses are eligible for NAT. If the access list were misconfigured, the router would not create translations for those hosts. However, the scenario states that translations are present, indicating that the access list is correctly matching the internal hosts.

If the outside interface were missing the 'ip nat outside' command, the router would not perform NAT on outbound traffic at all, resulting in no translations being created. Since translations are present, this command is correctly configured.

Similar to option C, if the inside interface were missing the 'ip nat inside' command, no translations would be created. The presence of translations indicates that the inside interface is correctly configured.

The specific factual error: The key is already correct as per the scenario; the problem is the missing AAA group definition.

The specific factual error: The port already has 802.1X enabled, so re-enabling it does not fix the authentication failure.

The specific factual error: The server is reachable, so connectivity is not the problem.

The specific factual error is that standard ACLs cannot filter by protocol (ICMP). They only match source IP addresses.

The specific factual error is that the ACL statement has the source and destination swapped, and it is applied on the wrong interface (G0/0 instead of G0/1).

The specific factual error is that the existing ACL 10 is too permissive and is applied on the wrong interface (G0/0 inbound) to filter traffic from R3 to R2. It must be removed to enforce the new restrictions.

The ACL is applied on the wrong interface; it should be applied inbound on G0/0, not G0/1.

The ACL is applied in the wrong direction; it should be inbound, not outbound.

The ACL is applied on an extra interface (G0/1) that is not required, which may block legitimate traffic.

The OSPF route to 10.10.10.0/24 matches the destination IP but has a shorter prefix length (/24) than the static route (/25). Since longest prefix match is the primary rule, this route is not used.

The default route 0.0.0.0/0 is the least specific and is only used when no other route matches the destination IP. Since more specific routes exist, the default route is not selected.

It is incorrect that packets are dropped due to overlapping routes. Cisco routers allow overlapping static and OSPF routes and forward packets based on the most specific prefix match, so the packet is not dropped.

Incorrect because automatic VLAN assignment for management traffic is unrelated to user identity or accountability; it concerns network segmentation, not administrative tracking.

Incorrect because route summarization efficiency deals with optimizing routing tables and has no connection to user account management or security accountability.

Incorrect because wireless roaming performance relates to client mobility and access point behavior, which does not involve administrative account design or accountability.

Root Guard prevents a port from becoming a root port by blocking superior BPDUs but does not shut down the port immediately. It is designed to maintain the root bridge position, not to disable ports upon accidental switch connections.

PortFast allows a port to transition quickly to the forwarding state, reducing STP convergence time. However, it does not disable the port if a BPDU is received, so it does not meet the requirement to shut down the port immediately.

Loop Guard prevents a port from transitioning to forwarding if BPDUs are lost, protecting against unidirectional link failures. It does not disable the port upon receiving BPDUs and therefore does not meet the requirement.

DHCP (Dynamic Host Configuration Protocol) assigns IP addresses, subnet masks, default gateways, and other network configuration parameters to clients. It does not perform name resolution; DNS is required for that.

NTP (Network Time Protocol) is used to synchronize clocks between network devices, not to resolve hostnames to IP addresses. It operates on UDP port 123 and has no role in DNS resolution.

Syslog is a protocol for logging system messages and events from network devices. It has no function in name resolution; it is used for monitoring and troubleshooting.

Assuming that a connection failure always starts at Layer 1 or 3, ignoring the specific error message that points to an application-layer mismatch.

Misplaced troubleshooting – attempting to relax security instead of fixing the server’s key size to meet the documented standard.

Drastic and insecure step that misdiagnoses the root cause; the issue is key size, not protocol version.

Incorrect because replacing SSH with Telnet reduces security by transmitting data unencrypted, exposing credentials and management traffic to interception, which violates best practices and the policy’s intent to secure management access.

Incorrect because enabling PortFast affects Spanning Tree Protocol port states to speed up network convergence and does not provide any control over router management access or SSH session initiation.

Incorrect because raising the syslog severity threshold only changes the level of logged messages and does not restrict or control which hosts can initiate SSH connections to the router.

Syslog is a protocol used for logging and monitoring system events, not for delivering network configuration parameters. It collects and forwards log messages from network devices to a central server for analysis, but does not assign IP settings.

NTP (Network Time Protocol) is designed to synchronize clocks between devices over a network, ensuring accurate timekeeping. It does not provide IP address, subnet mask, default gateway, or DNS server information to hosts.

GRE (Generic Routing Encapsulation) is a tunneling protocol used to encapsulate packets of one protocol within another, typically for creating VPNs or connecting remote networks. It does not provide host configuration parameters like IP addresses or DNS servers.

Configuring 'ip route 0.0.0.0 0.0.0.0 GigabitEthernet0/0' specifies only the exit interface. On multiaccess Ethernet, this causes the router to ARP for every unknown destination, which is inefficient and less ideal.

Configuring 'ip route 255.255.255.255 255.255.255.255 198.51.100.1' creates a host route, which matches only one IP address, not all unknown destinations. Therefore, it is not a valid default route.

The statement that no static default route should ever be used on Ethernet is incorrect. Static default routes are valid and commonly used on Ethernet interfaces, especially for WAN links.

Standard ACLs are specifically designed to match source IP addresses, so this statement is factually incorrect. They can match source addresses using wildcard masks.

Named ACLs use wildcard masks just like numbered ACLs; the naming does not affect the functionality of wildcard masks. The statement is technically incorrect.

The 'deny any' line at the end of an ACL is implicit, so placing it before the permit would block all traffic, including the intended 192.168.30.0/24 subnet. The order of entries matters, but the issue here is not about the order of deny any.

This option is incorrect because static routes do not always beat dynamic routes; the static route must have a lower administrative distance to be preferred, which is not the case here due to the floating static’s higher AD.

This option is incorrect because routing protocols are compared first by administrative distance, not by their internal metrics; RIP’s metric does not override OSPF’s lower AD.

This option is incorrect because equal prefix length alone does not guarantee load balancing; routes must have matching attributes and equal administrative distances for equal-cost multipath (ECMP) to occur.

Converting unused ports into trunk ports is incorrect because it increases network exposure by allowing multiple VLANs on ports that should remain inactive, thereby expanding potential attack vectors.

Enabling Telnet on all unused ports is wrong as Telnet is an insecure management protocol that does not address physical port security and can expose the network to interception and unauthorized access.

Advertising every unused port into OSPF is irrelevant because OSPF is a Layer 3 routing protocol that does not manage or secure Layer 2 switch ports, so it does not reduce exploitation risk.