Which entity is described as a common source of assistance when defending against DoS attacks?

• A. End users
• B. Assistance from ISPs and upstream providers is often required.
• C. Antivirus vendors
• D. Local IT staff only

Answer: (B)

Defending against DoS attacks works best when traffic is filtered or scrubbed as it enters your network, which is something ISPs and upstream providers are positioned to do. They sit at the edge of the network and have the scale and visibility to absorb, filter, or redirect large amounts of malicious traffic before it reaches your systems. This can involve scrubbing centers, rate limiting, or announcing null routes to drop bad traffic, all of which require cooperation with the provider that controls the network path to your organization. End users and local IT staff can help with internal responses but don’t have the capacity or reach to mitigate large floods, and antivirus vendors protect endpoints rather than network-wide floods. So assistance from ISPs and upstream providers is the common, effective source of DoS defense.