200-105 Sample Questions & Answers

The most significant benefit of switch stacking is the simplification of management. A stack of switches operates as a single logical unit with one IP address for management, one configuration file, and a unified control plane. This drastically reduces administrative overhead compared to managing each switch individually. It also simplifies network topology by allowing for the creation of multi-chassis EtherChannels, which eliminates the need for Spanning Tree Protocol to block redundant links between the access and distribution layers.

Modern Cisco IOS allows for a URL-style syntax to specify the protocol, server, and filename in a single command. The format tftp:// / provides all necessary information to the copy process, avoiding the interactive prompts. This is useful for scripting and automation.

Unlike EIGRP for IPv4 (and OSPFv2), which uses the network command under the router process to enable the protocol on interfaces, EIGRP for IPv6 (and OSPFv3) is enabled directly on the interface itself. The command ipv6 eigrp is entered in interface configuration mode to make that specific interface participate in the EIGRPv6 process.

The correct configuration requires several key elements: 1) The router bgp command must use the local AS number (65500). 2) The neighbor command must specify the peer's IP address (203.0.113.1) and their remote AS number (12345). 3) The network command is used to inject a route into BGP. It requires the exact network prefix and the corresponding subnet mask using the mask keyword. For the route to be advertised, it must exist in the router's routing table.

This solution meets all requirements. SVIs are the modern, scalable method for performing inter-VLAN routing on multilayer switches, providing high performance without the bottleneck of a single router link (Router-on-a-Stick). OSPF is an open-standard, scalable link-state routing protocol suitable for connecting the HQ and branch sites. It is more advanced and scalable than RIPv2 and, being an open standard, is a better choice than the Cisco-proprietary EIGRP in many enterprise environments, especially when future vendor interoperability is a consideration.

The spanning-tree portfast bpduguard default command is a global configuration that enables BPDU Guard on any port that has PortFast enabled. PortFast is intended for edge ports connected to end devices, which should never send BPDUs. If a BPDU is received on a PortFast-enabled port with BPDU Guard active, it indicates a potential misconfiguration or unauthorized device (like a switch), and BPDU Guard will place the port into an err-disabled state to prevent a potential STP loop.

In a local CHAP authentication setup, each router authenticates the other. On R1, you must create a user account with the username command. This username must exactly match the hostname of the peer router (R2), and the password must match the one configured on R2 for this username. Conversely, R2 must have a user account configured with R1's hostname and the same shared secret. CHAP uses a three-way handshake and does not send the password over the link, making it more secure than PAP.

This configuration correctly creates a named extended ACL called WEBFILTER. The first line (sequence 10) specifically denies TCP traffic from the source host 10.1.1.10 to the destination host 172.16.30.5 on the destination port equal to 80 (HTTP). The second line (sequence 20) then permits all other IP traffic from any source to any destination. This fulfills the policy requirements. The other options have incorrect syntax (e.g., using 'http' instead of the port number) or logic.

Defining an IP SLA operation (e.g., ip sla 1) only creates the operation's parameters. It does not activate it. The operation must be explicitly scheduled to run using the ip sla schedule command. Without this command, the SLA monitor will never execute, and its state will not be updated, often defaulting to or remaining in a failed or inactive state. Since a standard ping works, connectivity is confirmed, pointing to a configuration issue with the SLA monitor itself, and the missing schedule command is the most common cause.

The fundamental difference lies in their topological knowledge. Link-state protocols, like OSPF, build a complete topological map (the LSDB) of the entire area by flooding link-state information. Each router independently calculates the best path using the Dijkstra algorithm. In contrast, distance-vector protocols, like RIP, operate on the principle of 'routing by rumor.' Each router only learns about the network from the perspective of its immediate neighbors, without having a full picture of the entire topology. It knows the 'distance' (metric) and 'vector' (next-hop) to a destination.