When a cPanel account uses more data transfer than its monthly bandwidth limit, visitors see a Bandwidth Limit Exceeded page instead of the site. It stays that way until the next month or until the limit is raised. As a reseller you can fix it in a minute, then find the cause.
Before you start
- WHM access on your reseller plan (see logging in to WHM).
- The affected domain or username.
Confirm the limit was reached
- Go to WHM → Account Information → View Bandwidth Usage.
- Find the account; accounts over their limit are highlighted.
- Compare used bandwidth with the limit.
Restore the site quickly
- Raise the limit for this account: WHM → Account Functions → Modify an Account, increase Monthly Bandwidth Limit and save (see modifying an account).
- Move to a bigger package: better if the customer regularly needs more (see changing an account package).
The site comes back within a few minutes after the limit is raised.
Find what is using the bandwidth
- In View Bandwidth Usage, click the account for a breakdown by HTTP, FTP and email.
- In the customer's cPanel, Metrics → Awstats or Visitors show the biggest files and top visitors.
| Cause | Fix |
|---|---|
| Large videos or downloads served from the site | Host video on a streaming platform; use a CDN for downloads |
| Hotlinking: other sites embedding your images | Enable Hotlink Protection in cPanel → Security |
| Aggressive bots and scrapers | Block them; check access logs |
| Uncompressed, unoptimised images | Optimise images and serve WebP (see image optimisation) |
| A compromised site serving spam pages or files | Scan with Imunify360 (see malware scanning) |
Tip: A CDN in front of the site serves images, CSS and JavaScript from its own network, so most bandwidth no longer counts on the account.
Prevent repeats
- Review bandwidth weekly as part of resource monitoring.
- Set realistic limits in packages and watch your total allocation (see reseller limits).
Frequently asked questions
When does bandwidth reset?
Usage counts per calendar month and resets at the start of the next month.
Does email count toward bandwidth?
Yes. Incoming and outgoing mail, IMAP downloads and webmail traffic all count.
Can customers see their own bandwidth?
Yes, in the cPanel statistics sidebar and in Metrics → Bandwidth.
Should I set packages to unlimited bandwidth?
Avoid unlimited. A clear limit protects your reseller allocation from one runaway site, and you can raise it for customers who need more.
Why did bandwidth spike suddenly?
Common causes are a viral post, a bot crawling every page, hotlinked images or a hacked site serving files. Check Awstats and access logs for the period.
Can I be warned before a customer hits the limit?
cPanel sends bandwidth warnings to the account contact as usage approaches the limit. Keep contact emails current and review usage weekly.
Does a CDN reduce bandwidth counted on the account?
Yes. Files served from the CDN's cache do not reach your server, so they do not count against the account's bandwidth.