When peak service traffic exceeds your instance's base clean bandwidth, Anti-DDoS Pro and Anti-DDoS Premium charge for the excess on a pay-as-you-go basis using the 95th percentile metering method.
Clean bandwidth refers to the traffic your Anti-DDoS instance routes to your origin servers after DDoS attack traffic has been scrubbed. Burstable clean bandwidth kicks in only when legitimate post-scrubbing traffic exceeds the base clean bandwidth you purchased — attack traffic is excluded from measurement entirely.
Starting 10:00 (UTC+8) on March 6, 2026, the Monthly 95th percentile billing method is no longer available for new purchases. Manual adjustments to burstable clean bandwidth in the console — such as enabling, disabling, changing billing methods, or changing bandwidth specifications — are also no longer available. For details, see [Update] Adjustment to the Anti-DDoS Burstable Billing Feature on March 6, 2026.
Supported instance types and burstable bandwidth limits
The following instance types support burstable clean bandwidth. The elastic bandwidth upper limit is used in the burstable bandwidth peak formula.
| Instance type | Edition | Elastic bandwidth upper limit |
|---|---|---|
| Anti-DDoS Proxy (Chinese Mainland) | Profession | 20,000 Mbps |
| Anti-DDoS Proxy (Chinese Mainland) | Advanced | 20,000 Mbps |
| Anti-DDoS Proxy (Outside Chinese Mainland) | Insurance | 5,000 Mbps |
| Anti-DDoS Proxy (Outside Chinese Mainland) | Unlimited | 5,000 Mbps |
| Anti-DDoS Proxy (Outside Chinese Mainland) | Sec-CMA 2.0 | 1,500 Mbps |
| Anti-DDoS Proxy (Outside Chinese Mainland) | Sec-CMA 2.0 (Insurance) | Same as Sec-CMA 2.0 |
| Anti-DDoS Proxy (Outside Chinese Mainland) | Sec-CMA 2.0 (Unlimited) | Same as Sec-CMA 2.0 |
| Anti-DDoS Proxy (Outside Chinese Mainland) | Chinese Mainland Acceleration | 1,000 Mbps |
| Anti-DDoS Proxy (Outside Chinese Mainland) | Sec-CMA 1.0 | 500 Mbps |
Use cases
Burstable clean bandwidth is enabled by default and handles temporary traffic spikes without requiring manual instance upgrades. Typical scenarios include:
Promotional events — Black Friday and other large-scale sales promotions
New service launches — Opening new game servers or releasing new products
Scheduled access peaks — University course selection systems, government lottery systems, and similar services with predictable traffic surges
Proof of concept (POC) users must stay within test specifications to avoid pay-as-you-go charges.
If traffic consistently exceeds your clean bandwidth, upgrade your instance to increase the guaranteed clean bandwidth instead of relying on burstable billing.
Burstable bandwidth peak
Instance type | Monthly 95th percentile unit price (USD/month/Mbps) | Daily 95th percentile unit price (USD/day/Mbps) |
Anti-DDoS Proxy (Chinese Mainland)-Profession, Advanced | 15 | 1 |
Anti-DDoS Proxy (Outside Chinese Mainland)-Insurance | 16 | 1.05 |
Anti-DDoS Proxy (Outside Chinese Mainland)-Unlimited | 21 | 1.4 |
Anti-DDoS Proxy (Outside Chinese Mainland)-Sec-CMA 2.0 | 155 | 10 |
Anti-DDoS Proxy (Outside Chinese Mainland)-Chinese Mainland Acceleration | 155 | 10 |
Anti-DDoS Proxy (Outside Chinese Mainland)-Sec-CMA1.0 | 155 | 10 |
The burstable bandwidth peak is the default upper limit for elastic resources:
Burstable bandwidth peak = min(Base Clean Bandwidth × 10, Elastic Bandwidth Upper Limit)
When traffic exceeds the burstable bandwidth peak, the system continues to provide service on a best-effort basis and charges based on actual usage. However, packet loss may occur during cluster scale-out. To prevent this, upgrade your guaranteed clean bandwidth promptly.
Billing methods
Burstable clean bandwidth supports two metering methods: daily 95th percentile (default, enabled when you purchase an instance) and monthly 95th percentile. Both use pay-as-you-go pricing and take effect immediately after activation.
Switch between methods up to three times per calendar month. The new method takes effect at 00:00 on the first day of the following calendar month. The last change made within a month is the one that takes effect.
How the 95th percentile is calculated
Daily 95th percentile: For each calendar day, the system collects bandwidth samples from your Anti-DDoS instance every 5 minutes, producing 288 values per day. It removes samples collected during DDoS attacks, removes the top 5 remaining values, and takes the highest remaining value as the 95th percentile bandwidth for that day.
Monthly 95th percentile: For each calendar day, the system collects 288 bandwidth samples every 5 minutes, removes samples collected during DDoS attacks, and takes the highest remaining value as the daily peak bandwidth. At month end, it sorts all daily peak values in descending order and averages the top 5 — that average is the monthly 95th percentile bandwidth.
Comparison
| Daily 95th percentile | Monthly 95th percentile | |
|---|---|---|
| Settlement period | Calendar day | Calendar month |
| Billing trigger | 95th percentile bandwidth for the day exceeds Clean Bandwidth | 95th percentile bandwidth for the month exceeds Clean Bandwidth |
| Fee formula | (Daily 95th percentile bandwidth − Clean Bandwidth) × daily unit price (USD/day/Mbps) | (Monthly 95th percentile bandwidth − Clean Bandwidth) × effective factor × monthly unit price (USD/month/Mbps) |
| Base bandwidth (Clean Bandwidth) | The Clean Bandwidth specification on Day T-1 (the day before the billing day). If you upgrade on a given day, the new specification becomes the billing baseline starting the next day. | The Clean Bandwidth specification on the last day of the calendar month on which burstable clean bandwidth was enabled |
| First-day billing | No charge on Day T (the day you first enable the feature). Charges start from Day T+1; the first bill is generated on Day T+2. | Day T (the day you first enable the feature) does not count as a valid day for the effective factor calculation. |
| Effective factor | N/A | Effective factor = valid days ÷ total days in the month. Example: Enabled on July 15; valid days = 16 (July 16–31); effective factor = 16 ÷ 31 = 0.51612903. |
| Additional conditions | — | Cannot disable more than once per calendar month. Cannot switch methods on the last day of a calendar month.
|
If the 95th percentile bandwidth exceeds the burstable bandwidth peak, the service continues on a best-effort basis and you are billed for actual usage. Packet loss may occur during cluster scale-out. Upgrade your guaranteed clean bandwidth to prevent this.
Pricing
| Instance type | Edition | Monthly unit price (USD/month/Mbps) | Daily unit price (USD/day/Mbps) |
|---|---|---|---|
| Anti-DDoS Proxy (Chinese Mainland) | Profession, Advanced | 15 | 1 |
| Anti-DDoS Proxy (Outside Chinese Mainland) | Insurance | 16 | 1.05 |
| Anti-DDoS Proxy (Outside Chinese Mainland) | Unlimited | 21 | 1.4 |
| Anti-DDoS Proxy (Outside Chinese Mainland) | Sec-CMA 2.0 | 155 | 10 |
| Anti-DDoS Proxy (Outside Chinese Mainland) | Chinese Mainland Acceleration | 155 | 10 |
| Anti-DDoS Proxy (Outside Chinese Mainland) | Sec-CMA 1.0 | 155 | 10 |
Bill generation and settlement
| Metering method | Bill generation | Fee settlement |
|---|---|---|
| Daily 95th percentile | At 14:00 the following day, the bill appears in System Logs and Alibaba Cloud sends an email notification. | At 17:00 the following day, Alibaba Cloud deducts the fee from your account balance. |
| Monthly 95th percentile | At 10:00 on the first day of the following month, the bill appears in System Logs and Alibaba Cloud sends an email notification. | At 10:00 on the third day of the following month, Alibaba Cloud deducts the fee from your account balance. |
To view expense details, go to the System Logs page. For instructions, see System Log.
Overdue payment and instance expiry
Instance expiry: If you do not disable burstable clean bandwidth after your subscription instance expires, the backend stops generating bills.
Overdue payment: If payment is overdue and burstable clean bandwidth is still enabled, billing continues. Overdue payments do not affect access to your subscription instance, but pay-as-you-go bills keep accruing.
Billing example
Scenario: An Anti-DDoS Proxy (Chinese Mainland) Profession instance with burstable clean bandwidth enabled, using the daily 95th percentile method.
| Date | Clean Bandwidth spec | Daily 95th percentile bandwidth | Notes |
|---|---|---|---|
| January 1 | 100 Mbps | — | Baseline day |
| January 2 | Upgraded to 150 Mbps | 170 Mbps | — |
| January 3 | 150 Mbps | 170 Mbps | — |
| January 4 | 150 Mbps | 1,650 Mbps | Exceeds burstable bandwidth peak |
Daily billing uses the Day T-1 Clean Bandwidth as the baseline. Fee calculations:
January 3 bill (for January 2 usage):
Day T-1 (January 1) Clean Bandwidth = 100 Mbps
95th percentile = 170 Mbps
Fee = (170 − 100) × 1 = 70 USD
January 4 bill (for January 3 usage):
Day T-1 (January 2) Clean Bandwidth = 150 Mbps (upgrade took effect)
95th percentile = 170 Mbps
Fee = (170 − 150) × 1 = 20 USD
January 5 bill (for January 4 usage):
Day T-1 (January 3) Clean Bandwidth = 150 Mbps
95th percentile = 1,650 Mbps
Burstable bandwidth peak = min(150 × 10, 20,000) = 1,500 Mbps. The actual traffic (1,650 Mbps) exceeds this peak, but the system continues service on a best-effort basis and bills based on actual usage.
Fee = (1,650 − 150) × 1 = 1,500 USD