Just one IP for now. You are right to worry about being blocked from crawling however, it has happened to me already on a few sites. The key things to help mitigate against this are:
1. Always identify your crawler via a consistent user-agent string, that explains its a web search crawler and not a generic web browser.
2. Always obey the directives in robots.txt.
3. Make sure your crawler is not too aggressive (low frequency of requests).
1. Always identify your crawler via a consistent user-agent string, that explains its a web search crawler and not a generic web browser.
2. Always obey the directives in robots.txt.
3. Make sure your crawler is not too aggressive (low frequency of requests).
(updated for formatting)