Also, what are you talking about? Are you claiming that NTT nor TWTC can mitigate a DDoS attack? If so, you're massively wrong.
Both are in possession of large networks which allow them to mitigate DDoS attacks.
The small business with the 1gbps pipe isn't "mitigating" the attack. Their provider is mitigating the attack in return for payment.
Also, what are you talking about? Are you claiming that NTT nor TWTC can mitigate a DDoS attack? If so, you're massively wrong.