what will be the impact of enabling and disabling the "Do not send TCP ACK or SYN-ACK packets during host discovery" in the host discovery process. Please help me out.
The impact will be a faster discovery scan completion. Qualys attempts a Half open SYN connection for the purpose of discovery scans.
If you wish or if you have network limitations because of something that can re-write network traffic like a FW etc then you may choose to have a 3 way TCP handshake too at scan.
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