Instructions in advance, after Lavalys's EVEREST (from Canada) was discontinued, FinalWire's AIDA64 (from Hungary) became its successor. EVEREST Ultimate Edition is now AIDA64 Extreme Edition, and EVEREST Corporate Edition is now AIDA64 Business Edition.
Bad sector (bad track) is one of the most common failures of mechanical hard disk (HDD), which usually characterizes hard disk reads/writes slow, system prompts "... I/O error", program gives "cyclic redundancy check (CRC) error", etc. In these cases, we need use some specially designed tools to correctly detect whether our hard disk has had bad sectors or not, and nip in the bud.
As far as I can see, HD Tune Pro has been the best and most popular universal hard disk testing and diagnostic toolkit all the time. It can show you all the performance parameters of any kind of storage media, including Firmware version, Capacity, Serial number, Buffer size, SATA standard, supported UDMA mode and the supported features like read-write speed, burst rate, ...
The data stored in hard drive is almost always important (also vital for few guys), so it's necessary to regularly check their health status. CrystalDiskInfo is an open-source, free hard disk detection tool from Japan. It can provide comprehensive health info of HDD/SSD through reading its S.M.A.R.T. data (which can be used to monitor and analyze the health condition of hard drive in real time).
HWiNFO is a professional, comprehensive hardware information analysis and diagnostics freeware from Slovakia. It supports the latest hardware, technology and standards, as well as DOS, 32-bit & 64-bit multiple OS at the same time.
For DNS server, the response speed is not the only standard to measure its performance. Certainly the response time should be as short as possible, but the stability and security is also important factors. A DNS server without stability (intermittent) will cause web page loading problems even it has very fast response.