CISCO CCNA Quiz

To solve this question, the user needs to know about MAC addresses and how they work in a routed network.

MAC addresses are unique identifiers assigned to network interfaces by the manufacturer. Each MAC address is assigned to a specific device, and it is used to identify that device on a network.

In a routed network, packets are sent from one network to another through intermediate devices such as routers. As a packet travels through the network, the MAC address of the source and destination will change depending on the device it is passing through.

Now let's go through each option and explain why it is right or wrong:

A. The source address will change and the destination address will change: This option is incorrect because the source and destination MAC addresses will not always change. They may change as the packet passes through different devices in the network, but they may also remain the same in certain cases.

B. Change to reflect the current source and destination: This option is partially correct. The MAC address of the packet will change as it passes through different devices in the network. However, it is not changing to reflect the current source and destination, but rather to identify the device the packet is currently passing through.

C. Remain the same: This option is incorrect. While it is possible for the MAC address to remain the same in certain cases, it is not always the case.

D. The source address will remain the same but the destination address will change: This option is also partially correct. The source MAC address will not change, but the destination MAC address will change as the packet passes through different devices in the network.

E. None of the above: This option is incorrect because options B and D are partially correct.

Therefore, the correct answer is:

The Answer is: B or D (both are partially correct)

Non-Volatile RAM (NVRAM) is used in Cisco routers to store the startup-configuration file. Unlike system RAM, NVRAM retains its contents when the router is powered off or rebooted, ensuring the configuration persists.

A Cisco router enters the interactive 'setup mode' automatically if it cannot find a valid configuration file in NVRAM during the boot process. This allows the administrator to perform a basic initial configuration via a guided dialogue.

Cisco IOS can be loaded from three locations at boot: Flash memory (the primary storage for IOS images), a TFTP server (network boot for loading or recovery), and ROM (contains a limited IOS for emergency situations). NVRAM stores configuration, not IOS images.

UDP is a connectionless, best-effort protocol that does not use acknowledgments - packets are sent without confirmation of receipt. In contrast, TCP, SPX, Telnet, and FTP all provide reliable, acknowledged delivery through connection-oriented mechanisms.

A default route (often represented as 0.0.0.0/0) is the path used by a router when no specific match for a destination IP address is found in the routing table. It acts as a 'gateway of last resort' for outgoing traffic.

The Catalyst 5000 series switches use store-and-forward switching as their primary mode. In store-and-forward, the entire frame is received and checked for errors before forwarding, which ensures error-free transmission at the cost of some latency. Cut-through switching forwards frames before they're completely received and is not the default for these switches.

Source-route bridging is primarily used in Token Ring environments where the source station specifies the entire route through the bridged network in the frame header. This is necessary because Token Ring uses source routing for frame forwarding across multiple rings. Ethernet uses transparent bridging (learning bridges), and switched circuits don't use source-route bridging.

A metric in routing protocols is a measure of route desirability, calculated from values like hop count, bandwidth, delay, reliability, and load. It determines which route is preferred when multiple paths exist. Option A incorrectly confuses metrics with administrative distance (which is used to select between routing protocols, not routes). Option B is closest to correct, though 'trustworthiness' is an unusual phrasing.

Cisco 7500 series routers use modular interfaces where ports are addressed using slot/adapter/port numbering. The 7500 series has a modular chassis with slots containing interface cards (adapters), and each adapter has multiple ports. The 1000, 2500, and 2600 series are fixed-configuration routers or use simpler numbering schemes (like interface type + slot/port). The slot/adapter/port format is specific to high-end modular platforms like the 7500 series.

When a switch receives a frame for an unknown destination, it floods the frame to all ports. During this process (and all incoming traffic), the switch examines the source MAC address to build its MAC address table, effectively 'learning' where devices are located.

Bridges and switches operate at the Data Link Layer (Layer 2). They are transparent to upper-layer protocols (like IP, IPX, or AppleTalk), meaning those protocols do not need to know the bridge or switch exists to function across the network.