- Link Quality Monitoring was not configured correctly on each interface.
- PAP authentication was misconfigured on the link interfaces.
- The clock rates configured on each serial interface do not match.
- The compress command was used when PPP was configured on the interfaces.
Explanation: Using the compress command when configuring PPP on interfaces can reduce the system performance due to a software compression process. The reduced performance may reduce the content delivery quality, especially in the case of audio and video streaming, such as MPEG file streaming. When compressed data files, such as .mpeg, .zip, and .tar files, are carried on the link, using the compress command is not recommended. If PAP is used but misconfigured, the PPP link will not work at all. The clock rate is needed only on the DCE side of a serial link. Configuring Link Quality Monitoring will only monitor the incoming and outgoing link quality. Link Quality Monitoring is not sensitive to which type of content is transmitted.
More Questions: CCNA 4 Chapter 2 Exam Answers