Comparing agent-based and agentless monitoring

Agentless Solutions
Pros
• Possible reduced license costs
• Better implementation speed
• Lower maintenance (no upgrade costs/effort)
• Minimal impact on server load (for example, on applications server)
• A solution for "locked down" servers (applications servers where nothing can be loaded in addition to the core application)
• Good option for less-mission-critical applications
Cons
• Lack sophisticated capabilities to deliver in-depth, granular data
• Consume network resources (poor solution for clients with slow/remote network links)
• Susceptible to network problems (if the network is down, then there is a loss of ability to monitor server activity)
• Response time (if polling is responsibility of central server)

Agent-Based Solutions
Pros
• Greater access to more-granular data
• Greater command and control capabilities (for example, the ability to take automated corrective action, even when not connected to the management server)
• Highly secure communication between server and managed node
• Less network impact (for example, zero polling and message suppression at agent)
• Higher resilience — less dependence on network (local agents continue to function if network link is disrupted)
• Superior asynchronous data processing
• High availability
Cons
• Affects monitored server resources
• Administration management overhead (costs and effort) for distributed agents
• Cost