Sportsbook Subdomain Indexing: What Google Documents

The question operators actually face

Gambling groups often run products on separate hosts: casino.example for games, sports.casino.example for the sportsbook, poker.casino.example for poker. The reasons are usually operational. Sportsbook platforms are often supplied by a different vendor, deployed separately and sometimes hosted in a different region. The SEO question is what that split changes.

We separate what Google documents from what is commonly claimed. Google's documentation does not say that subdomains rank worse or better than subdirectories. Its SEO Starter Guide tells site owners to do "whatever makes sense for your business" and notes that "it might make sense to partition topics into subdomains, depending on your site's topic or industry." We found no official Google page stating a preference either way, so we do not repeat claims that one structure "passes authority" better than the other.

What Google does document about hosts

Sources for each row: the crawl budget guide says hosts like www.example.com and code.example.com "are treated as separate sites" with "separate crawl budgets". The robots.txt specification says rules "apply only to the host, protocol, and port number" where the file is hosted. Google's site names documentation says "Google Search does not support site names at the subdirectory level." The Starter Guide is the source for directory crawl frequencies.

Risks that are specific to sportsbook subdomains

A forgotten robots.txt

A vendor-hosted sportsbook can ship with a staging robots.txt that disallows everything, or with no robots.txt at all. Because the main domain's file does not apply to the subdomain, check the subdomain's own file after every vendor release.

Rendering on a vendor front end

Many sportsbook front ends are built as client-rendered single-page apps (see our JavaScript rendering guide). Event lists, odds and competition links may only exist after JavaScript runs and an API answers. If the odds API rejects requests from outside licensed regions, Googlebot, which Google says crawls mostly from US-based IP addresses by default, may render an empty shell. Test with URL Inspection on the subdomain itself. See our rendering test.

Weak links between hosts

If the casino links to the sportsbook only through a header button that opens a modal, the subdomain may have very few crawlable links pointing at its competition and event pages. Add plain <a href> links from relevant casino pages and guides to the sportsbook hub and key competitions.

Sitemaps and markets across hosts

A central sitemap can list sportsbook URLs if you verify both hosts; see cross-host sitemaps. If market versions live on separate hosts, the hreflang guide applies.

Duplicate content across hosts

Promotions and terms pages sometimes exist on both hosts. Choose one host for each page and canonicalize or redirect the other.

A measurement plan

Because Google publishes no rule about which structure performs better, the useful question is how your subdomain is crawled and indexed now. This plan answers that with your own data:

1. Set up properties. Keep a DNS-verified Domain property for the whole brand, and add a URL-prefix property for the sportsbook host so it has its own Page indexing view (Crawl Stats in a Domain property already breaks requests down by host). Google's verification help says to keep the DNS record in place "even after verification succeeds."
2. Baseline crawling. From verified Googlebot logs (see server log analysis) on the sportsbook host: requests per day, status mix, share to event versus competition versus static URLs.
3. Baseline indexing. Submitted versus indexed counts per sportsbook sitemap, and URL Inspection on a fixed sample of 50 to 100 competition and event pages.
4. Check discovery paths. Count crawlable internal links from the main host to the sportsbook host.
5. Change one thing at a time and record the date: a robots.txt correction, server-rendered competition links, a sitemap split.
6. Re-measure after four to six weeks, comparing equivalent periods because sports calendars change traffic and crawl patterns.

If you are considering a move

Moving a sportsbook from a subdomain into a subdirectory, or the reverse, is a site move for the URLs involved. Map every URL to its new location, use 301 redirects, update internal links and sitemaps, and keep the old host's robots.txt crawlable so Google can see the redirects. Decide on the move for operational reasons, not because of claims about subdomains that Google has not documented.

Questions technical teams ask