Normally, you get two DNS entries by your ISP, a primary and secondary DNS server. On Speedy, the entry varies across Speedy accounts since they may have lots of DNS server. One problem is that when DNS Server is not working well, then you may not be able to find the page you are looking for, unless you know exactly the IP address and type them directly at the location bar in your browser.
Since they never published their DNS entries, it's better to find an alternative DNS server on the Internet. There is an OpenDNS project which can fix this problem. All you need to do is register your accounts and add their IP to your nameserver entries.
On Linux, you can just put the line on your /etc/resolv.conf. Here's an example:
nameserver 126.96.36.199After adding OpenDNS' nameserver, i can browse normally again. Thanks to them.
Other option for Indonesian users is to use Nawala project. It can also be used to protect children for accessing inappropriate websites, such as websites that contains adults material.