DNS is a system that stores information associated with domain names in a distributed database on networks such as the Internet.
For example, when you type in a domain name like, for example, mozilla.org, you computer will automatically query the Domain Name System to find the actual IP address of the server you are trying to reach, for instance: 184.108.40.206.
You can see that query in more detail by opening a command window and typing in:
Lightweight Directory Access Protocol (LDAP) is an networking protocol for querying and modifying directory services running over TCP/IP.
Is is often use to verify a login/username against a central directory to allow/reject login and then maybe obtain more detailed information on the user (firstname, lastname, etc.)
A modulator-demodulator is a device used to transmit digital data over an analog channel. It modulates/demodulates a carrier signal in order to encode digital information onto it.
A modem is typically used to transmit computer data over POTS phone lines.
The bounce rate is the percentage of visitors who leave a web site after viewing a single page.
This is widely regarded as a bad thing because it may mean that visitors did not find what they were looking for and "bounced" away to another site. They left almost immediately.
However, this is a broken metric in many cases. For example if you were looking for opening times of a retailer in your city and you found that info right on the homepage of the retailer, you will technically leave the site after a single page view. However it does not mean you did not find what you were looking for.
Furthermore you may have visited some competing sites in a row, "bouncing" from on e to the next, still finding the exact information (closing times) on each of them in a single page view each.