New Relic Synthetics: Monitor Traffic, Headers and IPs

New Relic Synthetics is the synthetic monitoring service of New Relic. A synthetic monitor is a scheduled check that a New Relic customer points at a URL. It is not a search or AI crawler. Each request carries an X-Abuse-Info header that names the New Relic account and monitor, so you can find out who set up the check.

What the monitors do

New Relic’s introduction to synthetic monitoring lists these monitor types:

Monitor type	What it does
Ping	Checks that a URL is online
Simple browser	Loads a page in an instance of Chrome or Firefox
Scripted browser	Runs a custom script that moves through a site
Step monitor	Runs browser steps that are set up without code
API test	Makes HTTP calls to API endpoints and checks the results
Certificate check	Checks when a domain certificate expires
Broken links	Tests all links on one page

Monitors run from New Relic public locations around the world, or from private locations that a customer runs on its own systems.

User agent

New Relic does not document one fixed user-agent string for synthetic monitors. New Relic says that the ping monitor identifies itself as Google Chrome, but it is not a full browser and does not run JavaScript. Browser monitors use a real Chrome or Firefox instance. For these reasons, the user agent is not a reliable way to identify this traffic.

Identify requests with the X-Abuse-Info header

New Relic adds an X-Abuse-Info header to synthetic monitor requests. The header has this format:

X-Abuse-Info: Request sent by a synthetic monitor (/docs/synthetics/new-relic-synthetics/administration/identify-synthetics-requests-your-app) - monitor id: ${MONITOR_ID_STRING} | account id: ${ACCOUNT_NUMBER}

If you have access to that New Relic account, you can see the monitor results or turn the monitor off. To turn it off, open the monitor in New Relic, select General under Settings, and set the Monitor toggle to Disabled.

Customers can also add their own custom header to ping, browser and API monitors.

IP addresses

New Relic publishes the IP ranges of its public locations in a JSON file. The public IP address page says that only New Relic uses these ranges. New Relic also says that the addresses can change, and that it tries to tell customers by email before a change.

If you run your own monitors and your firewall blocks unknown traffic, add all ranges from the JSON file to the allowlist. New Relic recommends the full list, because a request can come from more than one environment.

Requests from private locations come from the customer’s own network. They do not use these ranges.

Block or allow synthetic monitor traffic

New Relic’s synthetic monitoring documentation does not mention robots.txt. A customer chooses the URLs that a monitor checks, so a firewall rule or a server rule is the reliable control.

If you do not use New Relic, you can block these IP ranges at your firewall or CDN. If you use New Relic yourself, this block also stops your own monitors from public locations. In that case, block by the X-Abuse-Info header and the account ID instead.

New Relic is one of several monitoring services that appear in server logs. Others are Datadog, Pingdom and UptimeRobot.