The interval, in seconds, for which the Device Server will issue a CHAP re-challenge to the remote end. During CHAP authentication, an initial CHAP challenge takes place, and is unrelated to CHAP re-challenges. The initial challenge takes place even if re-challenges are disabled. Some PPP client software does not work with CHAP re-challenges, so you might want to leave the parameter disabled in the Device Server. The default value is 0 (zero), meaning CHAP re-challenge is disabled.