According to Salesforce.com help, there is no limit to the number of levels when you are creating a Lookup Relationship. You can create N number of levels while doing lookup relationships, as long as you don't create Master-detail instead of creating lookups.
However, before proceeding with this design, do consider the reporting needs that you may have as part of your requirement and also analyze the impact of these levels upon reports.
we have to give look up relationship like A-->B-->c--->D like this how many levels we can give lookup relationship..?
I have used it for up to 5-6 levels but don't know what is the limit.
According to Salesforce.com help, there is no limit to the number of levels when you are creating a Lookup Relationship. You can create N number of levels while doing lookup relationships, as long as you don't create Master-detail instead of creating lookups.
However, before proceeding with this design, do consider the reporting needs that you may have as part of your requirement and also analyze the impact of these levels upon reports.
Hope this helps!