$(11$ points$)$ UDP and TCP use $1$s complement for their checksums. Suppose you have the following three $8-$bit bytes: $01011111,01110000,11001001.$

a$.$ What is the $1$s complement of the sum of these $8-$bit bytes? $($Note that although

UDP and TCP use $16-$bit words in computing the checksum, for this problem you

are being asked to consider $8-$bit sums.$)$ Show all the work. $(4)$

b$.$ Why is it that UDP takes the $1$s complement of the sum; why not just use the

sum? $(3)$

c$.$ With the $1$s complement schema, how does the receiver detect errors? Is it

possible that a $1-$bit error will go undetected? How about a $2-$bit error? $(4)$