Code.gs

function checkURLs() {

  var rows = new Array;
  var sheet = SpreadsheetApp.getActiveSpreadsheet().getSheetByName('URLs');
  var logsSheet = SpreadsheetApp.getActiveSpreadsheet().getSheetByName('Logs');
  rows = sheet.getSheetValues(2, 1, sheet.getLastRow(), sheet.getLastColumn());

  for (index in rows) {

    var isAlive = false; //
    var row = rows[index]; //Get current for from rows
    var url = row[0]; //Get url from row
    var _index = parseInt(index) + 2;

    if (typeof url !== 'undefined' && url !== '') {

      try {
        //try to ping
        response = UrlFetchApp
          .fetch(url)
        //if success set alive true.
        isAlive = true;
      } catch (error) {
        //do nothing.
        sheet.getRange(_index, 2).setValue('failed');
        sheet.getRange(_index, 3).setValue(getTime());
        //Write a log to logs section
        logsSheet.appendRow([
          url, error, getTime()
        ])
      }

      if (isAlive) {
        //write live status
        sheet.getRange(_index, 2).setValue(response.getResponseCode());
        sheet.getRange(_index, 3).setValue(getTime());
        continue;
      }

    }

  }

}

function getTime() {
  var d = new Date();
  var timeStamp = d.getTime();
  return d.toLocaleString(); // "12:35 PM", for instance
}