Technical discussions on subdomain configuration, DNS management, SSL, and web infrastructure.
Posted by SEOStrategist · 55 replies
Google has repeatedly stated that Googlebot crawls and indexes subdomains as well as subdirectories, and that the choice should be based on technical and organizational needs rather than SEO alone. Subdirectories inherit domain authority more directly and are generally preferred for content closely related to the main site. Subdomains work well for distinct applications such as blog.example.com or shop.example.com where separate teams manage content or the technology stack differs. For most small to medium sites, subdirectories are the safer choice for consolidating SEO value.
Posted by SSLNovice · 38 replies
A wildcard SSL certificate secures a domain and all of its first-level subdomains using a single certificate with the common name *.example.com. This means blog.example.com, shop.example.com, and api.example.com are all covered, but sub.sub.example.com is not. Wildcard certificates are available from all major Certificate Authorities including Let's Encrypt via Certbot with the DNS-01 challenge, DigiCert, and Sectigo. They simplify certificate management significantly for organizations with many subdomains. Wildcard certificates are not valid for the root domain itself unless a SAN entry is also included.
Posted by DNSConfig · 33 replies
DNS TTL, or Time to Live, determines how long resolvers cache a DNS record before querying the authoritative server again. For production subdomains with stable IP addresses, a TTL of 3600 to 86400 seconds is typical and reduces DNS query load. When planning a migration or IP change, reducing the TTL to 300-600 seconds 24-48 hours before the change allows faster propagation. After the migration is complete, raise the TTL back to a higher value. Very low TTLs increase DNS query volume and can contribute to rate limiting on some DNS providers.
Posted by HostingNewbie · 27 replies
Most shared hosting control panels like cPanel and Plesk have a dedicated Subdomains section where you enter the subdomain prefix, the parent domain, and specify the document root directory. The control panel automatically creates the DNS A record pointing to the shared hosting IP. If you manage your DNS externally through Cloudflare for example, you must add the A or CNAME record there manually. Allow up to 48 hours for DNS propagation, though changes typically take effect within 1-4 hours with lower TTLs.
Posted by ABTestIdea · 31 replies
Subdomains can be used for A/B testing, though dedicated A/B testing platforms like VWO or Optimizely are typically more efficient for most use cases. A common pattern is using staging.example.com for a staging environment with server-side routing to split traffic. Using subdomains for A/B tests introduces complications because separate subdomains do not share cookies by default, and search engines may index both variants if not properly handled with rel=canonical or noindex. For SEO-sensitive sites, JavaScript-based A/B testing within the same domain is generally safer.
Posted by SecurityAlert · 49 replies
Subdomain takeover occurs when a subdomain's DNS record points to a service such as a CDN, S3 bucket, or GitHub Pages that has been deprovisioned, allowing an attacker to claim that service and serve malicious content under your subdomain. Prevention requires regularly auditing CNAME and A records to ensure all pointed services are active, implementing a DNS inventory process, and removing DNS records when services are decommissioned. Tools like SubFinder and Nuclei can scan for dangling DNS records. This vulnerability affects organizations of all sizes.
Posted by BlogSetupQ · 43 replies
For most websites, hosting a blog at example.com/blog consolidates SEO value and internal linking strength better than blog.example.com. However, if the blog serves a dramatically different audience, runs on a different CMS, or is managed by a separate team, a subdomain or even a separate domain may be justified. E-commerce sites often separate their blog to prevent content management systems from sharing the same security surface as the store. WordPress multisite installations make subdomain blog setups relatively easy to manage from a single dashboard.
Posted by DNSBasics · 25 replies
A CNAME or Canonical Name record maps a subdomain to another domain name rather than directly to an IP address. For example, a mail subdomain CNAME pointing to an email provider causes the resolver to follow the chain until it finds an A record. CNAME records cannot be used at the root or apex domain, only at subdomains. CNAME flattening, offered by Cloudflare and other DNS providers, resolves this limitation for root domains. Note that MX and NS records cannot point to a CNAME target per DNS specification.
Posted by SubdomainLimit · 22 replies
DNS specifications do not impose a hard limit on the number of subdomains you can have under a domain. Each label separated by dots can be up to 63 characters, and the total domain name length cannot exceed 253 characters. In practice, limits are set by your DNS provider's plan, with some shared hosting plans limiting subdomain creation to 25-100, while enterprise DNS providers support thousands. Wildcard DNS records using *.example.com can handle unlimited dynamic subdomains without creating individual records for each one.
Posted by RedirectHelp · 36 replies
Subdomain-to-path redirects are best handled at the web server or reverse proxy layer. In Nginx, you create a server block for the subdomain and use a return 301 directive to redirect to the target URL. In Apache, a VirtualHost directive with a Redirect or RedirectMatch rule accomplishes the same. Cloudflare's Page Rules and Transform Rules can also handle subdomain redirects without touching server configuration. Ensure you redirect both HTTP and HTTPS variants to avoid redirect chains. Use 301 permanent redirects for SEO value and 302 for temporary redirects.
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