O lista practica de depanare pentru orice developer sau calculatorist pasionat (în engleză, că-i programare :P):
- Is the filename extention right? Should it be .php instead of .html?
- You can get to the web site? Are you working in “off-line” mode?
- Make sure CapsLock is off. (Same for ScrollLock and NumLock)
- Is there a (invisible) CTRL-M at the end of each line in the text file?
- Does the text file end with a newline?
- Are both ends of the (power/network/video/etc.) cable plugged in?
- Did you unplug and re-plug in the cable to make sure its in right?
- Is the cable plugged into the right jack? (Some jacks look the same: AUI and video, Some Sun’s have a ‘stealth’ video jack that you aren’t supposed to use, etc.)
- “Did you get permission to run crack against that password file?” … “Is it in writing?”
- Is the user pressing RETURN when you think they are? (Are they pressing it at all?)
- Is the user typing a “/” or a “\”?
- Does the user know which is the lessthan and which is the greaterthan symbol?
- Is the screen paused via Ctrl-S? (press CTRL-Q to find out)
- Does your test gear test what you think it tests? What happens when you run the exact same test on a known-good and a known-bad element? Do you get the results you expect both ways?
- Does plugging a lamp into that outlet make it light up? (If you use a radio, be careful of radios with battery backups)
- Is the laptop running off battery? (therefore obscuring a power problem)
- Use cut-and-paste to copy that variable name (or URL, commmand line, etc.) to see if it was entered correctly.
- Check the file permissions.
- Check the environment variables (Use “strings” on the binary to find out what they really are supposed to be).
- It’s too easy to answer “yes” when asked, “Is it plugged in.” It’s better to ask them to power it off, then power it back on OR ask them to “check both ends of the power cable” OR ask them if the power light is on, off, or blinking. (and if it’s blinking… RUN!)
- Type it again (without using cut-and-paste) and see if you get the same results. (good way to find a typo)
- Is the default route set? Is the netmask set correctly?
- Traceroute from A to B. Traceroute B to A. Do they match up?
- Is someone else also at that IP address? (Unplug the network cable and ping the address)
- Are you really on the host you think you are?
- Is the program reading the last line of the file? Is it being processed right?
- Are you doing the test from the right machine? Would the test be more effective from a different machine?
- (firewall ruleset issues) If you move the machine to another IP address does it still happen? If you move the machine to a different subnet does it still happen? If you put a different machine at that IP address does it still happen? If you boot the same machine on a different OS (like a CD-ROM based Linux or FreeBSD) does it still happen?
- Does the same thing happen when you specify the IP address instead of the hostname? (Hint: the lmhost or /etc/hosts may be overriding)
- Is that a file, a directory, a hard link, a symbolic link, or a mountpoint?
- http://www.psc.edu/~mathis/MTU/index.html: Six classes of bugs limit network performance.
- packet losses, corruption, congestion, bad hardware
- IP Routing, long round trip times
- Packet reordering
- Inappropriate buffer space
- Inappropriate packet sizes
- Inefficient applications
Any one of these problems can hide all other problems:
- Are the binaries really the ones you think are running? (Did you install in single user mode when /opt wasn’t mounted? Can you check the md5 or sha1 checksum vs. a machine that is running properly?)
- Is DNS configured right? Misconfigured DNS masks other problems and appears as bizarre problems that will send you looking everywhere except /etc/resolv.conf
- Is there a rogue DHCP server on the network messing with you?
- Is the device driver you’re trying to install for the device you actually have?
- Did you remember to check this list?
Peste putine nu am dat pana acum 🙂 De aici.
Apoteotic: