Duration, Dollar Duration & Rebalancing in ALM

CFA Level III Fixed Income
#1

CFAI text Vol 4

At the bottom on P.28, there are two conditions which shall be met. On the other hand, in 1stline on P.30, it is said that portfolio “ rebalancing ” is required to keep the portfolio duration synchronized with the horizon date. While dollar duration is rebalanced in Example 7 on P.31.

My questions :

  1. “To keep the portfolio duration synchronized with the horizon date” means same thing as the 1stcondition ?
  2. Are both the duration and dollar duration be rebalanced ?
  3. Why only dollar duration is rebalanced in Example 7 ?
  4. How to rebalance the portfolio duration (in example 7) ?