The section of the IT environment that is closest to the external world; where we locate IT systems thaCyril wants to ensure all the devices on his company's internal IT environment are properly synchronized. Which of the following protocols would aid in this effort? $($D$4,$ L$4\mathrm{.}1\mathrm{.}2)$t communicate with the Internet. $($D$4\mathrm{.}3$ L$4\mathrm{.}3\mathrm{.}3)$