When your actual QPS peak exceeds the clean QPS specification of your Anti-DDoS Proxy instance, burstable QPS absorbs the excess traffic and bills only for what you use, on a pay-as-you-go basis. This page explains how burstable QPS is metered, priced, and settled.
Starting from 10:00:00 (UTC+8) on March 6, 2026, new customers cannot enable the monthly 95th percentile billing mode and cannot manually adjust burstable QPS settings in the console—including enabling or disabling the feature, switching the billing mode, or modifying the specification. For details, see [Update] Announcement on changes to the burstable billing feature for Anti-DDoS on March 6, 2026.
How it works
After you purchase an Anti-DDoS Proxy instance, burstable QPS is enabled by default using the daily 95th percentile metering method.
When your actual QPS peak exceeds your clean QPS, the system absorbs the excess on a pay-as-you-go basis—no instance upgrade needed. This covers traffic scenarios such as:
Holiday sales promotionsBlack Friday — large-scale events such as Black Friday
New service launches — a new game server going live or a product release
Sudden traffic spikes — campus course registration systems or government lottery systems
Proof of concept (POC) users must not exceed their test specifications. Unexpected pay-as-you-go charges may be generated if they do.
If your clean QPS consistently falls short of daily traffic requirements and you prefer not to use pay-as-you-go burstable QPS, upgrade your instance to increase the clean QPS.
Supported instance types
| Product | Supported editions |
|---|---|
| Anti-DDoS Proxy (Chinese Mainland) | Profession, Advanced |
| Anti-DDoS Proxy (Outside Chinese Mainland) | Insurance, Unlimited, Sec-CMA 2.0, Sec-CMA 2.0 (Insurance), Sec-CMA 2.0 (Unlimited), Sec-CMA |
Burstable QPS peak
The burstable QPS peak is the upper limit of elastic resources allocated by default.
Formula: Burstable QPS peak = min(Clean QPS × 3, Burstable QPS limit)
Burstable QPS limits by region:
| Region | Instance type | Maximum burstable QPS |
|---|---|---|
| Chinese mainland | IPv4 | 300,000 |
| Chinese mainland | IPv6 | 100,000 |
| Outside the Chinese mainland | — | 150,000 |
If actual usage exceeds the burstable QPS peak, the system continues on a best-effort basis and charges for actual usage, but throttling is possible. To guarantee capacity beyond the burstable peak, upgrade the clean QPS in advance or contact your account manager for capacity expansion.
Relationship between burstable QPS and connections
The effective QPS level—whether from clean QPS or burstable QPS—determines the new connection and concurrent connection capacity for your instance.
| QPS | New connections | Concurrent connections |
|---|---|---|
| 0 < QPS ≤ 5,000 | 5,000 | 100,000 |
| 5,000 < QPS ≤ 10,000 | 10,000 | 200,000 |
| 10,000 < QPS ≤ 30,000 | 30,000 | 500,000 |
| 30,000 < QPS ≤ 50,000 | 50,000 | 1,000,000 |
| 50,000 < QPS ≤ 100,000 | 80,000 | 1,500,000 |
| 100,000 < QPS ≤ 150,000 | 100,000 | 2,000,000 |
| 150,000 < QPS ≤ 200,000 (Chinese Mainland only) | 150,000 | 3,000,000 |
| 200,000 < QPS ≤ 300,000 (Chinese Mainland only) | 200,000 | 4,000,000 |
Billing modes
Two pay-as-you-go billing modes are available. The feature takes effect immediately after it is enabled. Switching billing modes takes effect at 00:00 on the first day of the next calendar month.
| Daily 95th percentile | Monthly 95th percentile | |
|---|---|---|
| Billing cycle | Daily | Monthly |
| Unit price | USD 0.13/QPS/day | USD 1.8/QPS/month |
| Billing condition | Daily 95th percentile QPS > clean QPS | Monthly 95th percentile QPS > clean QPS |
| Formula | (Daily 95th percentile QPS − Clean QPS) × USD 0.13/QPS/day | (Monthly 95th percentile QPS − Clean QPS) × Validity factor × USD 1.8/QPS/month |
| Restrictions | Clean QPS used for billing is from Day T-1. An upgrade on Day T takes effect in billing only on Day T+1. No fees on the first day (Day T); fees start from Day T+1. | Can disable monthly billing only once per calendar month. Cannot switch billing mode on the last day of the month.
|
How the 95th percentile is calculated
Daily 95th percentile QPS:
The system collects actual QPS at 5-minute intervals — 288 data points per day. It removes data points recorded during DDoS attacks, then discards the top 5 highest remaining values. The highest value left is the daily 95th percentile QPS.
Monthly 95th percentile QPS:
Get the daily peak QPS — For each calendar day, collect QPS at 5-minute intervals (288 data points). Remove data points during DDoS attacks. The highest remaining value is the daily peak QPS.
Calculate the monthly 95th percentile QPS — Sort all daily peak QPS values in descending order. The average of the top 5 values is the monthly 95th percentile QPS.
Validity factor (monthly billing only):
Validity factor = Number of valid days ÷ Total days in the calendar month
The day you enable burstable QPS for the first time (Day T) is not counted as a valid day.
Example: You enable burstable QPS on July 15, 2024, and keep it enabled through July. Valid days run from July 16 to July 31 — 16 days. Total days in July = 31. Validity factor = 16 ÷ 31 = 0.51612903.
Billing settlement
Bill generation and deduction schedule
| Metering method | Bill generated | Fee deducted |
|---|---|---|
| Daily 95th percentile | 10:00 on the next day (visible on System Logs); email notification sent | 16:00 on the next day |
| Monthly 95th percentile | 11:00 on the 1st day of the next month (visible on System Logs); email notification sent | 11:00 on the 3rd day of the next month |
View bill details on the System Logs page. For more information, see System Logs.
Overdue payments
| Scenario | Behavior |
|---|---|
| Instance expired, feature not disabled | System stops generating bills |
| Overdue payments, feature not disabled | Bills continue to be generated |
Overdue payments do not affect subscription instances. However, pay-as-you-go bills continue to accumulate and may affect other pay-as-you-go services under your account.
To resume using burstable QPS, pay all outstanding bills and manually re-enable the feature.
Billing examples
The following examples use the daily 95th percentile mode.
Billing formula: Burstable QPS fee = (Daily 95th percentile QPS − Clean QPS) × USD 0.13/QPS/day (USD/QPS/month)(USD/day/QPS)
The clean QPS used for billing on any given day is the QPS specification from Day T-1 (the previous day). If you upgrade your QPS specification on Day T, the new specification takes effect in billing starting Day T+1.
Case A: Traffic exceeds clean QPS, no specification change
Instance: Anti-DDoS Proxy (Chinese Mainland) IPv4 Professional Edition
Clean QPS (from Day T-1): 4,000
Actual QPS peak on Day T: 6,000
Fee = (6,000 − 4,000) × USD 0.13 = USD 260
Case B: QPS specification upgraded on the same day as traffic spike
Instance: Anti-DDoS Proxy (Chinese Mainland) IPv4 Professional Edition
Clean QPS (from Day T-1): 3,000 (billing uses the T-1 specification even though it was upgraded on Day T)
Actual QPS peak on Day T: 6,000
Fee = (6,000 − 3,000) × USD 0.13 = USD 390USD 0.13/QPS/day = USD 1,300USD 0.13/QPS/day = USD 260 USD 0.13/QPS/day = USD 390
The upgraded specification (4,000 QPS) takes effect in billing starting the following day.
Case C: Traffic exceeds the burstable QPS peak
Instance: Anti-DDoS Proxy (Chinese Mainland) IPv4 Professional Edition
Clean QPS (from Day T-1): 4,000
Burstable QPS peak = min(4,000 × 3, 300,000) = 12,000
Actual QPS peak on Day T: 14,000 (exceeds the 12,000 peak)
The system processes traffic on a best-effort basis and bills based on actual usage, but throttling is possible.
Fee = (14,000 − 4,000) × USD 0.13 = USD 1,300
To avoid throttling at this traffic level, upgrade the clean QPS.