So , I tried accessing robot.lk via a web proxy and it worked.
Few minutes ago, I got a reply (luckily

Dear Customer,
This problem is beyond SLTNet control, But we SLTNet are discussing with relevant parties in global to resolve this issue.
Before that Please configure your ADSL connection manually with the following DNS servers.
203.115.0.46
203.115.0.47
Sorry for the inconvenience occured.
Thanks & Regards,
Nuranga Avinda.
ISP Services/NMC,
Sri Lanka Telecom PLC,
Colombo 01.
Voice : +94 112 543 085/6 [Fixed]
Fax : +94 112 391 324
E-mail : [email protected]