The technique sees common usage in software exploits, where it is used to direct program execution when a branch instruction target is not known precisely.
[3] Because of the popularity of this technique, many vendors of intrusion prevention systems will search for this pattern of no-op machine instructions in an attempt to detect shellcode in use.
As a result, it has become common practice for exploit writers to compose the no-op sled with randomly chosen instructions which will have no real effect on the shellcode execution.
[5] An incorrect guess will usually result in the target program crashing and could alert the system administrator to the attacker's activities.
If the input providing the attack vector into which the NOP slide and payload are to be introduced are filtered (such as accepting only printable characters), the field of possible instructions for inclusion is limited.