CCNA Practice Test - 9

The 'ip classless' command tells the router to forward packets destined for unknown subnets to the best available route, typically the default route (gateway of last resort). Without this command, if the router doesn't have an exact match for a destination subnet in its routing table, it drops the packet even if a default route exists. This was the default behavior in older IOS versions for classful routing. The command ensures the router uses classless routing behavior, forwarding packets for subnets it doesn't specifically know about to the default gateway.

The copy command syntax is 'copy '. Here, the source is 'system:running-config' (the current running configuration in RAM) and the destination is 'tftp://172.16.2.155/tokyo-config' (a TFTP server with filename). This command saves the running configuration from the switch to the TFTP server, naming the file 'tokyo-config'. Option A is incorrect because IOS copying uses different commands. Option B would use 'copy tftp://... startup-config'. Option D confuses what NVRAM contains (it's the local switch's startup-config, not a remote file).

A wireless access point (AP) acts as a bridge between wireless and wired networks. Its primary function is converting wireless 802.11 frames into wired 802.3 Ethernet frames so devices can communicate across network types. APs do not typically provide DHCP services (A and B) or act as network gateways (D).

Fiber-optic cable is most commonly used for backbone cabling runs because it supports high bandwidth over long distances without signal degradation. Backbone cabling connects entrance facilities, equipment rooms, and telecommunications closets. Horizontal, patch, and work area cables (B, C, D) are typically copper due to shorter distances and cost considerations.

Multiplexing is the process of interleaving multiple data streams onto a single communication channel, which matches the description of data interleaving. The other options are incorrect: piping refers to data transfer between processes, PDU is protocol data unit (a data structure), streaming is continuous media delivery, and encapsulation is wrapping data with protocol headers.

Hardware addresses (MAC addresses) are used for Layer 2 communication to transmit frames between directly connected interfaces on the same local network segment. Option A is incorrect because packets (Layer 3) use IP addresses. Option C is incorrect because MAC addresses are burned into the NIC, not obtained from users. Option D is incorrect because remote communication requires IP addresses, not just MAC addresses.

When Router A's interface priority is set to 255, it becomes ineligible to participate in DR/BDR election regardless of other configurations. The existing DR (Router D) and BDR (Router C) will remain unchanged. This is a priority change, not an election question - the 255 value specifically removes the router from contention.

IPv6 does not use broadcast addressing at all - it eliminated the broadcast concept entirely. Instead, IPv6 uses multicast, anycast, and unicast. The answer is 0 broadcast domains regardless of topology because the protocol doesn't support broadcasts as a communication method.

False, connectionless sessions do not use sequence numbers.

The problem occurs because VLAN 50 is not permitted to traverse the trunk link between Switch1 and Switch2. Host A and B can communicate because they're on the same switch. For Host A to reach Host C or D (on Switch2), VLAN 50 must be added to the allowed VLAN list on the trunk port using the switchport trunk allowed vlan command.

Linksys WRT300N access points are configured through a web interface. You access the configuration by entering the default IP address (typically 192.168.1.1) into a web browser from a computer on the same subnet. The other options are incorrect: you don't need to associate first (A), physical connection isn't required for configuration (B), and TCP/IP modification isn't necessary if you're already on the same subnet (D).

Full duplex Ethernet communication is only possible when systems are connected to their own switch port

An IPv4 address is 32 bits in length, typically represented as four octets (8 bits each) in dotted decimal notation (e.g., 192.168.1.1). IPv6 uses 128 bits, but the question specifically asks about IPv4. The 48-bit option (C) is the length of MAC addresses, and 64-bit (B) is common in other addressing schemes but not IPv4.

To support 27 hosts, we need a block with at least 29 usable addresses (2^5 - 2 = 30 for /27, which gives 255.255.255.224). Option A (/24) provides 254 addresses - too many wasted. Option B (/26) provides 62 addresses - still wasteful. Option D (/28) provides only 14 addresses - insufficient. Option E (/29) provides only 6 addresses - insufficient. The /27 mask (C) is optimal.

The serial interface cannot communicate because no Layer 2 protocol (like PPP, HDLC, or Frame Relay) has been configured. Serial interfaces require explicit Layer 2 encapsulation configuration to function. The other options are incorrect: interface resets (A) wouldn't prevent communication, LQM (B) is a specific PPP feature not relevant here, missing queues (C) is not the issue, and the interface is not administratively shutdown (E) as evidenced by 'up/down' or similar state.

Route poisoning is the mechanism where a router advertises a failed route with an infinite metric (hop count 16 in RIP) to immediately inform other routers that the route is unreachable. This prevents routing loops by ensuring all routers know the route is bad. Split horizon (A) prevents sending updates back the way they came, error condition (B) is not a routing loop prevention mechanism, hold-down timer (C) waits before accepting changes, and count to infinity (E) is what routing loop prevention aims to avoid.

The router-id command must be configured under OSPF router configuration mode, not under interface configuration mode. Option A incorrectly attempts to set router-id on an interface, Option B only assigns an IP address to a loopback interface, and Option D uses the wrong command (ip address) under router mode. Only Option C correctly enters OSPF router mode with 'router ospf 1' and then sets the router-id.

Routers use administrative distance (AD) as the tiebreaker when multiple routing protocols provide routes to the same destination. EIGRP has a default AD of 90, while RIP has AD 120. The router will always prefer the route with the lower administrative distance, which is why the EIGRP route was installed over the RIP route. Option B is incorrect because RIP's metric (hop count) is only compared when both routes are from the same protocol.