This question already has an answer here:

How I will come to know that synchronization is complete. Also what is potential rewrite attack?

I am using geth --testnet --fast --cache=1024

last couple of results

I1026 08:43:50.011852 eth/downloader/downloader.go:711] Peer b274dd4c49d951d2 [hs 0.00/s, bs 0.00/s, rs 0.00/s, ss 0.00/s, miss
0, rtt 20s]: potential rewrite attack: #1715594 [00000000…] <= 1715594 limit I1026 08:45:18.157176 core/blockchain.go:1001] imported 1 block(s) (0 queued 0 ignored) including 18 txs in 19.219834ms. 1805595 [11e04fc8 / 11e04fc8]

merged by Waqar Lim Jan 11 '17 at 9:34

This question was merged with “potential rewrite attack” message on Geth because it is an exact duplicate of that question.

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