# DHCP timer example 3

Subject: Computer Networks

Exam: TEE

Reader: https://deep-learning-study-room.vercel.app/cn/#tee/practice/mapping/lease-3

Canonical: https://deep-learning-study-room.vercel.app/read/cn/tee/practice/mapping--lease-3/

Optional extension · no matching calculation in the two supplied papers

**Optional worked extension.** This calculation format was not found in the supplied December 2025 final or February 2026 re-exam. The numbers and practice marks are authored. Study the core concept and actual-paper questions first; this is extra explanation, not a TEE prediction.

### Practice question. A DHCPv4 lease lasts 24 hours. No different T1 or T2 values are supplied. Find the default renewal and rebinding times after lease acquisition. [3 practice marks]

#### Answer

## Given

Lease duration L=24 h; use default fractional timers.

## To find

T1 and T2 as elapsed times.

## Formula and why



$$
T_1=0.5L,\qquad T_2=0.875L
$$



Use these defaults only when the server/question has not specified other timer values.

## Step-by-step solution

#### Step 1. Renewal timer

T1=0.5×24=12 h.

#### Step 2. Rebinding timer

T2=0.875×24=21 h.

#### Step 3. Place them before expiry

12 h < 21 h < 24 h.

**Final answer:** T1=12 h; T2=21 h.

#### What this result means

These are elapsed times, not wall-clock times. Add them to the stated acquisition time only when a clock time is requested.