There are several safegaurds put in place with SPF. One of these is a limitation of DNS lookups to help ensure you do not have timeout issues. the SPF authentication "... can return a SOFTERROR when it takes too long or a DNS query times out, but they must return PERMERROR if the policy directly or indirectly needs more than ten queries for mechanisms. Any redirect= also counts towards this processing limit" (http://en.wikipedia.org/wiki/Sender_Policy_Framework#Error_handling). This means you are only allowed 10 DNS lookups and fetching the TXT and SPF records count toward that total.
For tips on how to configure your SPF record, please review the following articles: https://agari.zendesk.com/entries/26688208-A-few-steps-to-consider-when-creating-an-SPF-record-
For tools to test your SPF record before published, please visit the following: http://www.kitterman.com/spf/validate.html
If you would like to see a configured SPF record, please use our SPF tool found in your Agari PRO portal.