Poloniex is not responding. Its a time when we loose our trust and start to panic. This is what comes when you try to open poloniex site.
Even they didn't responded in their twitter. DDos attack might be the probable reason nevertheless its a huge setback to the best cryptocurrency exchange.
The best thing is we have to sit tight and wait. I also observed for a couple of days steem and sbd deposit-withdrawal are disabled. I am going to transfer all my holdings to bittrex once it comes online. Hope it comes back online soon.