Covers EOS, layer 2 and layer 3 routing fundamentals, leaf-spine and VXLAN data center design, campus wired and wireless networking, MPLS WAN routing and VPN services, and network automation.
8 free sample questions90 in the full practice test
As an Arista network architect, you are explaining the fundamental architecture of Arista EOS to a new engineering team. You need to describe how state is propagated between independent software agents running on the switch. Which architectural component is strictly responsible for serving as the central in-memory database that maintains the real-time state of the system and facilitates inter-process communication between these agents?
Answer and explanation
Correct answer: C
SysDB (System Database) is the core architectural component of Arista EOS. It acts as an in-memory database that stores the complete state of the switch. All independent software agents communicate exclusively by writing to and reading from SysDB, rather than communicating directly with each other. NetDB is the network-wide state database used by CloudVision, while NetDL is the modern data lake architecture for broader AI/ML integrations.
Q2Question 2
BeginnerMultiple answers
Network Foundations · CLI Navigation and Configuration
When implementing complex changes on an Arista switch in a production environment, you decide to use the configure session command instead of standard configuration mode. Which TWO of the following are primary benefits of using configuration sessions in Arista EOS? (Select TWO)
Answer and explanation
Correct answers: B, D
Configuration sessions in EOS allow administrators to stage multiple commands. These commands are validated and applied atomically (all at once) when the 'commit' command is issued. If any command fails validation during commit, the entire batch is rejected, ensuring the switch does not enter an inconsistent state.
Configuration sessions support the 'commit timer' feature. If an administrator issues a commit with a timer and loses connectivity due to the change, the switch will automatically revert the session changes when the timer expires, restoring access.
Q3Question 3
Beginner
Network Foundations · LACP and MLAG
A junior engineer is configuring an MLAG domain between two Arista 7050X3 switches. They are confused about the difference between the MLAG peer-link and the MLAG peer-address. What is the correct technical distinction between these two configurations?
Answer and explanation
Correct answer: B
In an Arista MLAG setup, the peer-link (usually a port-channel) is the physical/logical path that carries data traffic for single-homed hosts and MAC address synchronization. The peer-address is the IP address (typically on a dedicated SVI over the peer-link) used by the switches to establish the TCP connection for the MLAG control plane.
Q4Question 4
Intermediate
Network Foundations · IPv6 and QoS
Enterprise QoS Redesign Case Study
Background: You are a network architect for a financial enterprise upgrading its WAN edge routers to Arista devices. The enterprise connects to a Service Provider (SP) via a 10 Gbps physical link, but the contracted Committed Information Rate (CIR) is only 2 Gbps.
Current Situation: The SP strictly drops any traffic exceeding the 2 Gbps rate limit. Users are complaining about poor application performance, significant packet loss during file transfers, and dropped VoIP calls during peak business hours.
Requirements:
Ensure that traffic leaving the Arista WAN edge router never exceeds the 2 Gbps SP limit.
Prevent excessive packet drops for bursty TCP data traffic (like file transfers).
Prioritize VoIP traffic so it is not delayed by data transfers.
Based on Arista QoS capabilities, which configuration approach is the optimal solution for this scenario?
flowchart TD
A[Arista WAN Edge] -->|10 Gbps Physical| B(Service Provider)
B -->|Strict 2 Gbps Policer| C[Internet/WAN]
subgraph QoS Strategy
D[Traffic Class] --> E{Rate > 2Gbps?}
E -->|Yes| F[Action Required]
end
Answer and explanation
Correct answer: B
Traffic shaping buffers excess traffic rather than dropping it, which smooths out bursts and prevents the SP's strict policer from dropping the packets. This solves the TCP packet loss issue. Combining shaping with a strict priority queue ensures that latency-sensitive VoIP traffic is transmitted first, bypassing the shaped data traffic buffers.
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