Other · Yandex

YandexRCA user agent, IP ranges and robots.txt

YandexRCA is Yandex's other. It identifies itself with the YandexRCA user-agent token, applies robots.txt only in part, per its operator, and can be verified by reverse DNS (yandex.ru, yandex.net, yandex.com).

Operator
Yandex
Reviewed
September 2026
Sources
1
Operator
Yandex
User-agent token
YandexRCA
Purpose
Other
robots.txt token
YandexRCA
Honors robots.txt
Partially, see notes
Published IP ranges
No official range file
Verification
Reverse DNS lookup on the requesting IP must return a host ending in yandex.ru, yandex.net or yandex.com, and a forward DNS lookup of that host must return the same IP. Yandex Webmaster also provides an IP address check tool.
Reverse DNS suffix
yandex.ru, yandex.net, yandex.com
Full user-agent example
Mozilla/5.0 (compatible; YandexRCA/1.0; +http://yandex.com/bots)
Documentation
yandex.com/support/webmaster/en/robot-workings/check-yandex-robots.html

Block or allow YandexRCA in robots.txt

Use the token YandexRCA in robots.txt. Yandex documents limits on how this bot applies robots.txt; see the operator note.
Block everything
User-agent: YandexRCA
Disallow: /
Allow everything
User-agent: YandexRCA
Allow: /

Verify a request is really YandexRCA

Anyone can put YandexRCA in a User-Agent header. Reverse DNS lookup on the requesting IP must return a host ending in yandex.ru, yandex.net or yandex.com, and a forward DNS lookup of that host must return the same IP. Yandex Webmaster also provides an IP address check tool.

Reverse DNS check
host <request-ip>
# expect a hostname ending in yandex.ru, yandex.net, yandex.com
host <that-hostname>
# expect it to resolve back to <request-ip>

What YandexRCA does

Yandex operates YandexRCA, a robot that collects data for generating previews; the documentation does not say what kind. It honors robots.txt only partially. Rules addressed to the token YandexRCA apply, but general rules do not. Yandex documents no IP list; site owners verify it by reverse DNS to a yandex.ru, yandex.net or yandex.com hostname with a matching forward lookup.

Requests arrive with the user agent Mozilla/5.0 (compatible; YandexRCA/1.0; +http://yandex.com/bots). Yandex's robot list gives a single line of purpose, that the robot collects data for generating previews, and stops there; it does not say which Yandex product shows the previews or what content the robot pulls to build them. A site owner should read the visits as preview generation on Yandex's side and nothing more specific than that. Crawl rate and JavaScript execution are not documented for this robot.

The robots.txt behaviour is the detail to get right. Yandex marks YandexRCA as a robot that does not take general robots.txt rules into account, so a Disallow in your User-agent: * group does nothing to it. To block it you need a group addressed to User-agent: YandexRCA by name. Blocking it stops Yandex collecting data from your pages for its previews; allowing it lets Yandex generate them. Because the documentation does not describe the previews, it also does not describe what a site loses by blocking them.

Yandex documents no IP range file for YandexRCA. Verification is reverse DNS on the requesting address, which should resolve to a hostname ending in yandex.ru, yandex.net or yandex.com, followed by a forward lookup on that hostname that returns the same IP. Yandex Webmaster also has an IP address check tool for the same job. A request presenting the YandexRCA user agent from an address that fails these checks is not a verified Yandex request.

Operator note. It does not take into account the general rules in robots.txt. Yandex does not say what kind of previews it generates.

Common questions

Should I block YandexRCA?
Yandex says only that it collects data for generating previews, without naming the product or the effect on your site, so the decision rests on whether you want Yandex building previews from your pages. If you block it, address the rule to User-agent: YandexRCA by name; this robot ignores general User-agent: * rules.
Does YandexRCA respect robots.txt?
Partially. Yandex lists it as a robot that does not take general robots.txt rules into account, so the User-agent: * group has no effect on it. A robots.txt group addressed to YandexRCA by name is the documented way to control it.
How do I verify YandexRCA?
Run a reverse DNS lookup on the requesting IP; a real request resolves to a hostname ending in yandex.ru, yandex.net or yandex.com. Then run a forward lookup on that hostname and confirm it returns the original IP. Yandex documents no IP range file for this robot, but the Yandex Webmaster IP address check tool is an alternative.

Sources

The operator documentation used for this entry. Recorded review date September 2026; consult the linked pages for current policy and compare them with this dated snapshot.

  1. [1]https://yandex.com/support/webmaster/en/robot-workings/check-yandex-robots.html

This registry documents how operators describe their own bots so site owners can identify and control them. It does not publish third-party IP lists or guess at undocumented behaviour. To see how your own site responds to automated visitors, the bot detection scanner reads a URL's live response and names the protection it finds.