Which crontab entry could be used to set the system time at regular intervals?

Question

Options

• A1 0 * * * date $d $t $24
• B1 0 * * * ntpdate ntp1.digex.net
• C1 0 * * * date ntp1.digex.net
• D1 0 * * * runcron date ntp1.digex.net
• E1 0 * * * settime $d $t $24

• A
  4% (1)
• B
  83% (19)
• D
  9% (2)
• E
  4% (1)

Explanation

ntpdate is the correct tool for synchronizing system time with a network time server - option B runs it at 1 minute past midnight every day against a real NTP host (ntp1.digex.net), which is exactly what time synchronization requires.

Why the distractors fail:

• A & E invent nonexistent command syntax (date $d $t $24, settime $d $t $24) - neither date nor settime works this way to sync from a network source.
• C misuses date, which is a local clock utility; passing it a hostname is not valid syntax and it cannot contact NTP servers.
• D adds runcron, a fictitious wrapper that doesn't exist in any standard Linux distribution.

Memory tip: Think "NTP = Network Time Protocol" - you need a command with "ntp" in it (ntpdate) and a real NTP hostname to sync over a network. Any option using date alone or made-up commands can be eliminated immediately.

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