700-821 Sample Questions & Answers

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.

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.

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.

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.

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.

The IW9167 supports Wi-Fi 6 (802.11ax), which offers significant advantages for this use case. OFDMA and BSS Coloring in Wi-Fi 6 improve spectral efficiency and performance in dense environments, reducing latency. Additionally, Cisco's implementation on the IW9167 includes features for reliable roaming, making it the best choice for mobile clients like AGVs that require persistent, low-latency connections.

OFDMA is a key feature of Wi-Fi 6 that allows an access point to communicate with multiple clients simultaneously by subdividing a channel into smaller resource units (RUs). This is extremely efficient for IoT use cases where many devices send small packets, as it significantly reduces overhead and contention compared to the OFDM method used in previous standards, where only one client could transmit at a time.

Cisco URWB is the ideal solution for this scenario. It is purpose-built for connecting high-speed moving assets with ultra-low latency and zero packet loss. Its make-before-break roaming ensures seamless handoffs between track-side radios. The technology provides the deterministic performance required for critical control applications, which standard Wi-Fi mesh or cellular technologies typically cannot guarantee.

For an outdoor industrial deployment like a mine, the environmental rating of the antenna is paramount. An IP67 rating ensures it is dust-tight and can withstand water immersion, while a wide operating temperature range ensures it can function in both extreme heat and cold. While gain and radiation pattern are important, the antenna will fail if it is not physically built to survive the environment.

This statement is true. The Cisco IW6300 is specifically designed for hazardous locations and carries certifications like C1D2 and ATEX Zone 2. This allows it to be installed directly in environments where flammable gases or vapors may be present, without the need for a bulky and expensive NEMA enclosure.