While scanning with Nmap, Patin found several hosts which have the IP ID of incremental kiosk.adobe.com is the host with incremental IP ID sequence. What is the purpose of using "-sl" with Nmap?

Stealth scans in Nmap are performed with '-sS' (SYN scan), not '-sI'.

ICMP scans use '-sn' or '-PE' flags and send ICMP echo requests, which is a different technique unrelated to IP ID sequence exploitation.

The '-sI' flag in Nmap performs an Idle scan, which works by exploiting a zombie host that has a predictable, incremental IP ID sequence. The scanner sends spoofed packets appearing to come from the zombie to the target, then monitors the zombie's IP ID counter to infer whether the target's ports are open, never directly communicating with the target and thus remaining hidden.

'Silent scan' is not a defined Nmap scan type associated with this flag or the IP ID incremental sequence technique described.