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HTTP status codes control how crawlers make requests, load content, and whether pages are included in searches at all. I will show how responses such as 200, 301, 404, or 503 allow crawling, crawl budget, and hosting to work together and where typical bottlenecks lie.
Key points
- Crawl budget depends directly on clean status responses.
- 2xx/3xx Enable indexing, block 4xx/5xx.
- Forwarding Use only without chains and loops.
- server times and uptime shape crawler trust.
- Monitoring operate with logs, GSC, and crawlers.
Why status codes control crawling
Crawlers first check the Status code, followed by rendering and evaluation of the content. I therefore prioritize the correctness of the response over title tags or internal links. A 200 OK loads content immediately, while 4xx and 5xx cost time, budget, and trust. If errors accumulate, the bot reduces the number of requests and delays the inclusion of new content. This results in silent SEO losses, which can be avoided with clear rules for Server responses can be avoided.
2xx: The direct route to the index
The 200 OK is for crawlers a Green light. I only deliver 200 to genuine, content-complete pages and prevent soft 404s, which send 200 but offer no added value. Thin content, missing H1 or almost identical texts are warning signs for such misconfigurations. Cleaning up here saves crawl budget and strengthens thematic relevance. In addition, I optimize snippets and internal links so that crawlers and users with a appeal achieve the right goals.
3xx: Redirections without loss
301 permanently moves content and transfers signals to the new URL, while 302 stands for a temporary solution. I use 301 when content has actually been moved, and I remove chains and loops because every extra hop burns time and budget. Check internal links, because an internal 301 chain is a self-made traffic jam. For moves, I plan consistent rules so that everything points to the target URL in a clean line. I show why this is so important at redirect chains, which measurably affect loading time and crawling.
4xx: Clear signals for removed content
A 404 clearly states: This Resource There aren't any. I leave 404s for pages that have really been removed and avoid soft 404s by never sending 200 for error pages. 410 signals even more clearly that a page has been permanently removed; I use this specifically for old URLs with no suitable alternatives. Internal links to 404 waste budget, so I correct them promptly or redirect them to the best thematic alternative. This way, I keep crawlers on the pages that are real Value deliver.
5xx: Server errors slow down bots and users
5xx means: The server could not process the request. serve. If this happens frequently, crawlers classify the site as unreliable and visit it less often. For maintenance, I set 503 with „Retry-After“ so that bots know when it makes sense to try again. If a 503 persists, I evaluate logs and fix bottlenecks in the CPU, RAM, database, or rate limits. For WordPress, I collect practical tips in this guide to 503 errors, so that maintenance windows remain controlled and short.
Caching, 304, and ETags: Save money without taking risks
304 Not Modified saves Bandwidth, because the client is allowed to continue using its copy. I set ETag or Last-Modified cleanly so that crawlers can use If-Modified-Since correctly. This reduces the number of requests for unchanged CSS, JavaScript, and images. If the logic is incorrect, the bot will load an unnecessary number of files or miss updates. That's why I test variants, check response headers, and keep 304 responses consistent across all Assets.
Crawl budget: How I keep it high
Crawl budget depends on three factors: code quality, Performance and internal structure. I reduce time wasters such as forwarding chains, duplicate content, and slow TTFB. I limit internal links to a few clear paths so that bots can identify priorities more quickly. I quickly correct erroneous or orphaned pages before they drain the budget. This also includes status codes for pagination, canonicals, and hreflang, which without error signals have to run.
Hosting factors that influence status codes
Good hardware, clean server configuration, and capacity-appropriate Caching prevent 5xx spikes. I make sure there are enough PHP workers, database parameters, keep-alive, and HTTP/2 or HTTP/3. Rate limits for bots should also be set sensibly so that real users are not blocked. Edge caches and rules for static assets help with high load spikes. Here, I show why status codes and hosting performance are related: HTTP status and server power.
Monitoring: Using logs, GSC, and crawlers correctly
I'll start with server logs because they are genuine Inquiries and write down every response. Then I check Search Console for coverage errors, sitemaps, and render status. A desktop and mobile crawl with an SEO crawler detects redirects, 4xx, and 5xx errors in one pass. For in-depth analysis, I correlate errors with release dates or traffic peaks. This shows whether a rollout, plugin, or CDN rule set is causing the Answers has changed.
Quick overview: Status codes and measures
The following table assigns typical responses to the appropriate steps and highlights hosting points. I use it as a compass for quick decisions in everyday life.
| Status code | crawler response | Action | Hosting notice |
|---|---|---|---|
| 200 OK | Content is retrieved and evaluated | Deliver real content, avoid soft 404s | Keep TTFB low, cache warm |
| 301 Moved Permanently | Signals to target URL | Remove chains, update internal links | Keep rewrite rules clear |
| 302 Found | Temporary, source retains signals | Use only for a short period of time | Check regularly |
| 304 Not Modified | Use cache, no download | Set ETag/Last-Modified correctly | Deliver assets via CDN |
| 404 Not Found | URL removed from the index | Correct internal links, avoid soft 404s | Keep error pages lean |
| 410 Gone | Faster removal | Use for permanently removed content | Forwarding only if there is a genuine alternative |
| 500 Internal Error | Bot reduces visits | Check logs, fix cause | Increase resources and limits |
| 503 Service Not Available | Maintenance mode accepted | „Set “Retry-After," keep duration short | Schedule maintenance windows |
Error handling: What I check first
I start with the ScopeDoes the error affect all users, only bots, or only mobile devices? Next, I check whether the last change was made to the server, the application, or the CDN. If the error only occurs under load, I increase resources in the short term and search for bottlenecks in traces. For recurring 5xx errors, I set alerts on log patterns and status endpoints. This allows me to quickly resolve acute problems and prevent them from affecting the Crawl budget further reduce.
Technical checks prior to releases
Before each rollout, I test critical paths with a Staging-Crawl and compare status codes with the live version. I keep a list of important URLs ready: home page, category, product, filter, search, sitemap, API. Then I check headers such as cache control, vary, redirect rules, and canonicals. I set clear conditions for feature flags so that they do not unintentionally generate 302 or 404 errors. Only when status codes, loading times, and render results appear stable do I give the Release free.
robots.txt, sitemaps, and secondary URLs
I first check whether robots.txt Stable with 200 responses. 5xx or 403 on robots.txt unsettle crawlers and slow down crawling. A 404 on robots.txt is considered „no restriction,“ but is a bad signal for sites with crawl problems. For Sitemaps I only accept 200 and keep the files small, cleanly gzipped, and with correct lastmod fields. 3xx to the sitemap is technically allowed, but I avoid it in favor of a direct 200 response. For Feeds, AMP- or API-I make sure that resources do not return 404 or 5xx when the HTML page returns 200 – otherwise, the rendering or evaluation of structured data will be interrupted inconsistently.
Canonical, hreflang, and pagination only on 200
Signals such as rel=canonical, hreflang or pagination only take effect if target and reference URLs load with 200 final. I avoid canonicals on 3xx, 404, or noindex URLs because this confuses crawlers. For hreflang, I check the backreference and that each variant ultimately ends in 200. Paginated lists (page=2,3,…) must consistently return 200; I prevent empty pages from triggering soft 404s by offering clear content and internal links when results are missing, but still sending the correct status.
429 and using rate limits correctly
429 Too Many Requests is my tool for fine-grained throttling when individual bots are too aggressive. I set Retry After with a reasonable time specification so that crawlers stagger their requests. 429 is not a substitute for 503 maintenance and should never affect legitimate users. In the WAF or CDN, I differentiate by user agent, IP, and paths so that media assets continue to deliver 200/304 while HTML is briefly throttled. Important: 429 must not become permanent—otherwise, the bot will evaluate the site as difficult to access and reduce the budget.
401/403/451: intentionally blocked – but consistently
401 I use for login-protected areas, 403 for prohibited access. I make sure that these responses do not accidentally apply to Googlebot, for example by using strict bot filters. In the case of geo-blocking or legal requirements, I set 451 and document the reasons internally. I refrain from 200 responses with interstitials („access denied“)—such pages act like soft 404s. Where alternatives exist, I link clearly to accessible content and let the blocked URL send the correct 4xx status.
Parity of responses: mobile, desktop, and dynamic playback
I ensure that mobile and desktop bots have the same Status codes see. Dynamic playouts (A/B tests, feature flags, geo-content) must not trigger 302/403 for individual user agents. I use VaryUse headers sparingly and deliberately (e.g., Accept-Language) to avoid unnecessary cache splits, and ensure that every path ends consistently with 200/304 for all variants. Parity breaks lead to indexing problems when the bot sees a 404 while users receive 200 – I eliminate such cases with clear rules and tests for each variant.
HEAD, OPTIONS, and API endpoints
Many crawlers send HEAD-Requests to check availability and size. My server responds to these with the same logic as for GET – only without a body. I avoid 405 on HEAD if GET returns 200. OPTIONS and CORS preflights so that assets from third-party sources can be loaded cleanly. For API endpoints, When APIs deliver data during rendering, I look for stable 200/304 and clear 4xx for genuine errors. If APIs sporadically deliver 5xx, I mark this separately in logs because it can explain rendering errors under the hood, even though the HTML page sends 200.
CDN rules, stale strategies, and 5xx shielding
In the CDN, I cache 200, 301, and static 404 responses in a controlled manner—but I prevent 503 or admin pages end up in the cache. With stale-if-error I can bridge short-term 5xx errors without bots seeing errors. I set Surrogate control for Edge signals and keep TTLs shorter for HTML than for assets. I configure ETags cluster-safe (either the same everywhere or disabled) so that 304 works reliably and does not expire due to differing hashes. Important: Redirects (301/302) should not be cached indefinitely in the CDN, otherwise old paths will remain as chains.
E-commerce cases: Sold out, variants, filters
If products are temporarily unavailable, the product page remains on 200 with clear labeling and useful internal links (category, alternatives). For permanently removed products, I decide between 301 to the best replacement URL (only if there is a genuine match) and 410, if there is no suitable alternative. I avoid mass redirects to the home page, as they act like soft 404s. For Filter and parameter URLs I use clear rules: Only index-relevant combinations on 200, everything else via 301 to the canonical URL or with noindex – but never 200 for empty or nearly identical pages that trigger the soft 404 detector.
Clearly separate noindex, robots, and status codes
noindex is a content signal, the status code is a transport signal. I avoid hybrid forms that confuse crawlers: no 301 on a noindex page, no 200 with „restricted access“ placeholder if the resource does not exist. Either a page is indexable (200 + index) or it is removed (404/410) or temporarily unavailable (503 with Retry-After). robots.txt only blocks crawling—not the indexing of already known URLs. That's why I set 404/410 instead of robot barriers.
Key figures and thresholds that I monitor
- 5xx rate: Permanently well below 0.11 TP3T. Investigate spikes immediately.
- 4xx rate: depending on the site type, between 1–2%. Internal 4xx should go to 0%.
- 3xx share: as low as possible; Redirect chains to 0.
- 304 share For assets: high is good – indicator of functioning caching.
- TTFB For HTML: stable low; I correlate outliers with 5xx/429.
- Sitemap-Health: 200, valid lastmod, no dead links.
- Parity Mobile vs. desktop: same status codes and final URLs.
I link these metrics to deployments, traffic spikes, and infrastructure events. This allows me to identify patterns that Crawl budget influence long before rankings react.
Edge cases: 1xx, 405, 410 vs. 404
1xxResponses are practically irrelevant for SEO; I just make sure that the server and CDN upgrade correctly (e.g., HTTP/2/3). 405 Method Not Allowed appears when HEAD/POST are blocked, even though GET returns 200 – this is harmless, but should be configured consistently. When choosing 404 vs. 410 I use 410 for deliberately removed content that is permanent in nature, and 404 for unknown or accidentally linked paths. It is important to note that Consistency, so that crawlers can learn from recurring patterns.
Rollback strategies and reliability
I plan releases so that I can quickly revert if there are any error status codes: Blue/Green-Deployments, fine-grained feature flags, and reversible rewrite rules. For maintenance, I use Maintenance Pages, which deliver 503s while background jobs are running. At the infrastructure level, I have health checks, automatic restarts, and rate limits in place that intercept attacks without crippling legitimate crawling. Every measure is aimed at, 200/304 to maximize and keep 4xx/5xx controlled, brief, and understandable in the event of a malfunction.
Summary: Clean signals, faster crawling
I make sure that everyone Status code carries a clear message: 2xx for content, 3xx without chains, 4xx for removed pages, and 5xx only in truly exceptional cases. Caching with 304 relieves the server, while consistent 200 responses give the bot confidence. To make this work, I combine log analyses, GSC data, and recurring crawls. On the host side, I keep response times low, set limits sensibly, and plan maintenance cleanly. This increases quality, indexability, and visibility – and that Crawl budget flows to where it is most effective.
