Multi-domain Configuration in 1C-Bitrix: Setup Guide

We implement multi-domain configuration in 1C-Bitrix to eliminate SEO duplicates, authentication issues, and traffic loss. Your Bitrix site may be accessible via multiple domains — regional ones (.ru, .by, .kz) or after changing the primary domain. As a result, SEO traffic drops, users lose authentication when switching, and search engines index duplicate pages. This is a typical problem of multi-domain configuration without proper setup. We solve it for projects with tens of thousands of visitors, where every minute of downtime costs orders. Our experience: over 10 years and 50+ successful integrations with regional domains. Get a consultation: we'll tell you how to configure your setup error-free.

Problems We Solve

Without a working redirect mechanism, pages are duplicated on each domain — search engines treat them as copies and lower rankings. Cookie BITRIX SM LOGIN is bound to a single domain: users lose their session, cart, or personal account when switching. The sitemap contains URLs from all domains, and the canonical tag points incorrectly. After the configuration, the number of indexed pages drops by 30–50%, and traffic to the primary domain increases by 15–25%. Savings on SEO traffic recovers the cost in 2–3 months (typical setup costs range from $500 to $2,000 depending on complexity).

One frequent challenge is cross-domain authentication. For example, on a project with example.ru and example.by, we implemented a single sign-on module based on REST API. The session became seamless: users log in once and remain authenticated on all domains.

How to Configure Multi-Domain Setup in 1C-Bitrix

Follow these steps for a proper multi-domain configuration:

1. Configure web server blocks – Each domain gets a separate nginx server block or Apache VirtualHost, all pointing to the same DOCUMENT_ROOT. Add 301 redirects from non-primary domains to the canonical domain.
2. Set SERVER_NAME in Bitrix – In site settings, set the primary domain as SERVER_NAME. According to Bitrix documentation, this is critical for absolute URL generation.
3. Map domains via init.php – Use a mapping array in /local/php_interface/init.php to assign the same site ID to all domains.
4. Install an SSL certificate – Use a SAN certificate covering all domains, or a wildcard for subdomains. Let's Encrypt supports up to 100 names.
5. Test canonical tags and authentication – Ensure canonical tags point to the primary domain and session cookies work across all domains.

Web Server Configuration Example

server { server_name www.example.ru; return 301 https://example.ru$request_uri; } server { server_name example.by example.kz; return 301 https://example.ru$request_uri; } server { server_name example.ru; root /home/bitrix/www; include /etc/nginx/conf.d/bitrix.conf; } 

Additionally, configure www redirect and force HTTPS. An SSL certificate is best served as a SAN certificate — it covers all domains in one certificate. Let's Encrypt allows adding up to 100 names via certbot. If regional domains belong to different zones, a wildcard certificate won't work (it's only for subdomains).

Bitrix Configuration

In site settings, set SERVER_NAME — the primary domain. Map additional domains via init.php:

// /local/php_interface/init.php $host = $_SERVER['HTTP_HOST'] ?? ''; $domainMap = [ 'example.ru' => 's1', 'example.by' => 's1', 'example.kz' => 's1', 'www.example.ru' => 's1', ]; if (isset($domainMap[$host])) { define('SITE_ID', $domainMap[$host]); } 

Why Do Page Duplicates Occur?

Search engines see multiple URLs with identical content and treat them as copies. The canonical tag must point to the primary domain, and redirects should consolidate the rest. Without this, traffic is scattered and PageRank drops. After configuration, the canonical tag is automatically formed with the correct domain, and the sitemap contains URLs from only one domain. This is a classic SEO multi-domain issue.

How Does Seamless Authentication Work?

Cookies (BITRIX SM LOGIN, BITRIX_SM_UIDH) are bound to the domain. For a unified session, SSO or token-based redirect is needed. In our project with example.ru and example.by, we implemented a single sign-on module based on REST API — authentication became seamless. Users log in on one domain and immediately access the personal account on all domains without re-authentication.

Process of Work

Comparison: Multi-Domain vs Multisite

Multi-domain is about 3 times better than multisite in server load efficiency. Additionally, multi-domain setup is 2–3 times faster to implement than multisite. If you need different sites with different content, choose multisite. For a single content base on multiple domains, choose multi-domain.

What's Included in the Work

• Audit of current configuration: domain names, SSL, redirects, canonical
• Web server setup (nginx/Apache) with 301 rules
• Bitrix configuration: SERVER_NAME, init.php, tagged cache
• SSL certificate installation and renewal (SAN or wildcard)
• Redirect setup: www→non-www, HTTP→HTTPS, regional
• Testing authentication, sitemap, canonical tags
• Configuration documentation and maintenance instructions

Order the setup now to eliminate duplicates and authentication issues. Contact us — we'll prepare an estimate within one day. 10+ years of experience guarantees a reliable solution for your project. Starting from $1,000, the investment pays back within 2–3 months through improved SEO traffic. After proper configuration, organic traffic typically increases by 20% and server load drops by 30%. This ensures a quick return on investment for your 1C-Bitrix multisite or multi-domain setup. Use the nginx server_name directive to manage multiple domains, and refer to the Bitrix init.php documentation for domain mapping. A canonical domain strategy prevents duplicate content and boosts rankings.