IP Header Octet Bits Len Name Notes 0 0-3 - Version 4 bits. IP version number. Current version is 4. 0 4-7 - Hdr length 4 bits. Length of IP header in 32 bit words (4 octets). Minimum valid is 5 (20 octets). 1 - 1 ToS 1 octet. Type of Service. Rarely used, often misused or abused. bit 0-2: Precedence bit 3: Delay 0 = normal 1 = low bit 4: Throughtput 0 = normal 1 = high bit 5: Reliability 0 = no..