Answer:
24-bit
Step-by-step explanation:
WEP or Wired Equivalent Privacy is a security mechanism for IEEE 802.11 wireless networks. WEP uses 2 key strength ( WEP-40 and WEP-104).
WEP-40 makes use of a 64 bit RC4 key of which 24 bits are from the initialization vector. WEP-104 uses a 128 bit key of which 24 bits are from the initialization vector. In both cases the size of the initialization vector is 24.
Due to inherent security limitations WEP has now mostly been superceded by Wifi Protected Access (WPA).