$28.$ Which of the following is used for email communications?

M$.$ DNS $($Domain Name System$)$

N$.$ HTTP$/$HTTPS

O$.$ SMTP$/$POP$3/$IMAP

P$.$ TCP$/$IP protocols

$29.$ This octets of IPV$411000001000010110000101111101111$ represent which class of the following IP addresses?

A$.$ A

B$.$ B

C$.$ C

D$.$ D

$30.$ Which of the binary IP address format $10000001000010110000101111101111,$ represent the following Hexadecimal notation?

A$.810$B$0$BEF$16$

B$.810$C$0$BEF$16$

C$.810$B$0$CEF$16$

D$.810$B$0$BDF$16$