Navigator, a Javascript object, obtains information about the current web browser.?

Which of the following command line tools can be used to display listening sockets and established connections on the local computer?

A. nslookup B. nbtstat C. netstat D. ipconfig

Modern echo cancellation equipment

a. only allows a half-duplex connection b. are necessary even for local calls c. can never be disabled d. selectively removes only the echo