Potential Search Engine Penalties
A penalized web site is much less likely to show up in a SERP, and in some cases it may not appear at all.
we will discusses the following areas:
- The Google “sandbox effect”
- The expired domain penalty
- Duplicate content penalty
- The Google supplemental index

The Google “Sandbox Effect”
Many search engine optimization experts hypothesize that there is a virtual “purgatory” that all newly launched sites must pass through in order to rank well in Google. In fact, many new sites seem to pass through this stage, and many find that the period is remarkably close to six months. Matt Cutts states in an interview with Barry Schwartz that there may be “things in the algorithm that may be perceived as a sandbox that doesn’t apply to all industries” (http://www.seroundtable.com/archives/002822.html). While Google may not explicitly have a “sandbox,” the effect itself is real. For this reason it is termed an “effect,” and not a “penalty.” It may be the collective side effect of several algorithms — not an explicit “sandbox algorithm.” Some sites seem to be exceptions to the rule, especially those that acquire links from several authority sites early on. A few links from CNN.com and other prominent web sites, for example, may exempt a web site from the sandbox effect. Some hypothesize that Yahoo! has a similar algorithmic factor, but that it is less severe and pronounced. MSN Search does not appear to have anything similar implemented.
The Expired Domain Penalty
Using a previously expired domain to launch a new web site used to evade this dreaded “sandbox
effect.” This was likely because Google was unaware that the site was new. Google put a stop to this
loophole a while ago, and now it seems to be quite the opposite situation at times. An expired domain name may now be subject to a temporary penalty. This is important, because it implies an additional delay before a site begins to rank well. In some cases Google will even refuse to index the pages at all during that period, leaving a web site vulnerable to content theft. It is also likely that Google devalues any links that are acquired before the re-registration of the domain. At the time of writing, other search engines do not appear to penalize previously expired domains.

Duplicate Content Penalty
Search engines attempt to avoid indexing multiple copies of the same content—duplicate content. Many
search engine optimization experts hypothesize that not only does a search engine not index such pages,
but it also penalizes a site for having the duplicated content. This is a subject of much debate, but in any case, having duplicate content will not improve the rankings of a site in any of the major search engines.