IPV4 Header - GATE CS Mock 2018 | Set 2

Question

Which of the following option is false regarding option field in the $IPv4$ header:

• A. The Value of "Type" in the Security option field of an IPv4 header is $131$.
• B. If the header length is greater than $5$ (i.e., it is from $6$ to $15$) it means that the options field is present and must be considered.
• C. Copied, Option Class, and Option Number are sometimes referred to as a single eight-bit field, the Option Type.
• D. None of these

Answer 1

Ans-option(A) is incorrect.

(A)-type value in security option field is 130.

(B)-it is correct as we use scaling factor of 4 when header length is from 5 to 15 (because header length is 20B to 60B) ,so extra bytes are padded from option field.

(C)this is correct,copied,option class and option number are sometimes referred to as a single 8 bit ,option type

https://myweb.ntut.edu.tw/~kwke/DC2006/ipo.pdf