200-105 Practice Questions

The switchport voice vlan command configures the port to carry voice traffic on a separate VLAN. However, the phone itself needs to be informed which VLAN to use for its voice traffic. Cisco IP phones use CDP (Cisco Discovery Protocol) to learn this information from the switch. If CDP is disabled globally or on the interface, the phone will not learn about the voice VLAN (VLAN 20) and will attempt to get an IP address in the data VLAN (VLAN 10), which likely does not have a DHCP scope for phones, causing the failure.

In traditional networking, every device runs its own control plane (calculating routes, building ARP tables) and data plane (forwarding packets based on those tables). The core principle of SDN is to decouple these functions. The control plane is logically centralized into an SDN controller, which has a global view of the network and makes all the intelligent decisions. The controller then programs the data plane of the network devices (switches/routers) via a southbound API (like OpenFlow), telling them exactly how to forward packets. The network devices become simple packet-forwarding engines.

In EIGRP, the 'Passive' state is the normal, desired state for a route in the topology table. It means that the router has a stable successor (and possibly a feasible successor) for the destination network and is not performing any route computations for it. The opposite state is 'Active,' which indicates that the successor for a route has been lost and the router is actively sending out Query packets to its neighbors to find an alternate path.

The Point-to-Point Protocol over Ethernet (PPPoE) process is always initiated by the client device. The client (typically a home router or a PC) broadcasts a PPPoE Active Discovery Initiation (PADI) packet to discover any Access Concentrators (servers) on the network. An Access Concentrator responds with a PADO packet, and the client then sends a PADR to request a session, which is finalized by a PADS from the server.

This statement is false. A VTP transparent switch does not participate in the VTP domain (it doesn't synchronize its VLAN database with VTP updates and its configuration revision number remains 0), but it does forward VTP advertisements it receives on its trunk ports out its other trunk ports. This allows switches on opposite sides of a transparent switch to synchronize their VLAN databases with each other.

For an OSPF adjacency to form, neighbors must agree on several parameters, including Area ID, timers, subnet, and area type. If one router is configured for a stub area and the other is not, their OSPF Hello packets will contain a mismatch in the stub flag, preventing them from forming an adjacency. MTU mismatch would cause the adjacency to get stuck in the EXSTART/EXCHANGE state, not prevent neighbor discovery. Authentication mismatch would show log messages about authentication failure. Process ID is locally significant and does not need to match.

For links to be bundled in an EtherChannel, they must have consistent configurations. Key parameters that must match include speed, duplex, native VLAN, and the list of allowed VLANs on the trunk. If one port has a different native VLAN, it will be suspended and cannot join the channel. Similarly, a port configured as an access port for a specific VLAN cannot be bundled with trunk ports.

The router makes forwarding decisions based on its routing table. Even though the tunnel is configured, the router needs a specific route that directs traffic for the destination network (10.10.10.0/24) into the Tunnel0 interface. Without this route, the router will use the most specific matching route, which in this case is the default route pointing to the ISP. This causes the traffic to be routed to the public internet instead of being encapsulated in the GRE tunnel. Adding a static route like ip route 10.10.10.0 255.255.255.0 Tunnel0 would resolve the issue.

In HSRP, the router with the highest priority value becomes the active router for the group. The default priority is 100. In this configuration, SW1 has a priority of 110, which is higher than SW2's default of 100. Therefore, SW1 will become the active router. The standby 1 preempt command on SW1 ensures that if it comes online after SW2 has become active, it will reclaim the active role due to its higher priority.

This statement is true. A fundamental concept of multi-area OSPF is that an Area Border Router (ABR) maintains a separate and complete LSDB for each area it borders. This is how OSPF achieves scalability; routers within an area only need to know the detailed topology of their own area, and the ABR summarizes information between areas. Every ABR must be connected to Area 0, so it will always have an LSDB for Area 0 and at least one other non-backbone area.