Free 700-821 sample questions

Correct answer: Alternate

In a REP segment, one port must be configured with the 'Alternate' role. This port is responsible for blocking traffic on its link to prevent a loop during normal operation. When a link failure is detected elsewhere in the segment, the Alternate port unblocks to restore connectivity. Without an Alternate port, the segment cannot form a stable, loop-free topology, leading to convergence issues.

Correct answer: Failure of the link between the SAN and the RedBox.

PRP provides redundancy by duplicating packets across two independent networks (LAN_A and LAN_B). A failure in either LAN_A or LAN_B would not cause a connectivity loss for a DAN (Dual Attached Node) or a SAN connected via a RedBox, as the traffic would still be received on the other network. The RedBox's purpose is to provide this dual-attachment for a single-homed device. Therefore, if the SAN loses connectivity, the single point of failure is the physical link between the SAN itself and its RedBox.

Correct answers: The PTZ cameras require Cisco UPoE (802.3bt Type 3).; The total required PoE power budget is 135W.

Devices requiring 45W exceed the 30W maximum of PoE+ (802.3at) and require Cisco UPoE or 802.3bt Type 3, which can supply up to 60W per port.

The total power budget is calculated as (2 * 45W) + (3 * 15W) = 90W + 45W = 135W.

Correct answer: Cisco IE 4000 Series

The Cisco IE 4000 Series is designed as an aggregation layer switch for industrial environments. It provides high-density Gigabit Ethernet ports and supports advanced Layer 3 routing protocols such as OSPF, EIGRP, and BGP, making it ideal for this requirement. The IE 2000 is primarily a Layer 2 access switch, and while the IE 5000 is also a Layer 3 switch, the IE 4000 is the most common fit for high-density aggregation.

Correct answer: Cisco Industrial Network Director (IND)

Cisco Industrial Network Director (IND) is a network management system built specifically for industrial automation environments. It is designed to help operations teams gain full visibility of network devices and ease deployment and management tasks in large-scale industrial networks. While Prime Infrastructure can manage switches, IND is tailored for the OT environment and protocols.

Correct answer: False

This statement is false. The Device Level Ring (DLR) protocol is an open standard managed by the ODVA (Open DeviceNet Vendor Association) and is part of the EtherNet/IP specification. It is not Cisco-proprietary, although Cisco IE switches support it to ensure interoperability in automation and control networks.

Correct answer: IE 5000

The Cisco IE 5000 series switches are built to exceed the specifications of most industrial switches and are certified for harsh environments, including high shock and vibration. They are often used in demanding applications like rail, military, and heavy industry, making them the ideal choice for installation in a crane's control cabinet.

Correct answer: Deploy Cisco IE 3300 switches in a REP ring topology. Use VLANs and Access Control Lists (ACLs) to segment control and data traffic. Utilize the built-in PoE+ ports for endpoint devices.

This solution meets all requirements. The Cisco IE 3300 series supports REP for fast convergence (<50ms, often much faster), which satisfies the resiliency requirement. VLANs provide robust traffic isolation at Layer 2. The IE 3300 models offer PoE+ ports, are DIN-rail mountable, and have an operating temperature range that meets the 60°C requirement. This is a comprehensive and appropriate industrial networking solution.

Correct answer: The switch does not have enough power in its overall PoE budget to power on the new device.

When a switch denies power to a new Powered Device (PD), the most common reason is that the switch's total available PoE budget has been exceeded by the existing devices. The switch will not power a new device if doing so would surpass its power supply's capacity. The 'PD Disconnected' message can indicate the switch detected the device but could not allocate power.

Correct answer: To enable zero-touch replacement by storing the configuration file.

The main purpose of the SD card on Cisco IE switches is to store the device's configuration file. This allows for rapid, zero-touch replacement. If a switch fails, an operator can simply move the SD card from the failed unit to a new, identical unit. The new switch will boot up with the stored configuration, minimizing downtime.