When you attempt to connect to a computer that is shutdown or disconnected, it takes considerable time for your request to time out.

To determine if a computer is responding, you can use the PING (Packet InterNet Groper) command and alter the time out, per:

Usage: ping \[-t\] \[-a\] \[-n count\] \[-l size\] \[-f\] \[-i TTL\] \[-v TOS\]
            \[-r count\] \[-s count\] <a href="/article/tips/jsi-tip-9436-how-can-i-rapidly-determine-if-a-computer-is-available--83793?topic=-j%20host-list%5c%5d"> \[-k host-list</a>
            \[-w timeout\] target_name

Options:
    -t             Ping the specified host until stopped.
                   To see statistics and continue - type Control-Break;
                   To stop - type Control-C.
    -a             Resolve addresses to hostnames.
    -n count       Number of echo requests to send.
    -l size        Send buffer size.
    -f             Set Don't Fragment flag in packet.
    -i TTL         Time To Live.
    -v TOS         Type Of Service.
    -r count       Record route for count hops.
    -s count       Timestamp for count hops.
    -j host-list   Loose source route along host-list.
    -k host-list   Strict source route along host-list.
    -w timeout     Timeout in milliseconds to wait for each reply.

Example:

@ping -n 1 -w 250 <computer name or IP address>

would ping once. If the computer did not respond, the command would terminate within 250 milliseconds.

Using ADFind.exe freeware, I have scripted Demo.bat to rapidly return the NetBIOS computer name and IP address of all the computers in the domain you are logged on to. If the computer is NOT available, the IP address will be NONE. Demo.bat launches one batch file for every computer, using the Start command to run them, without waiting for completion before launching the next one. The output is displayed on the console, like:

"JSI001","123.123.0.1"
"JSI009","123.123.0.12"
"JSI005","NONE"
Demo.bat contains:
@echo off
setlocal ENABLEDELAYEDEXPANSION
set qry=adfind -default -f "&(objectcategory=computer)" -ps 99999 -nodn -noctl
set /a cnt=0
for /f "Tokens=*" %%c in ('%qry%^|Findstr /B /L /C:">name: "') do (
 set /a cnt=!cnt! + 1
 set wrk="%TEMP%\PCOK_!cnt!.bat"
 set name=%%c
 call :PCOKOB "!name:~7!" !cnt!>!wrk!
 start /min /high CMD /c !wrk!
)
@ping -n 7 127.0.0.1>nul
for /f "Tokens=*" %%a in ('dir "%TEMP%\PCOK_*.log" /b') do (
 type "%TEMP%\%%a"
 del /q "%TEMP%\%%a"
)
del /q "%TEMP%\PCOK_*.bat"
endlocal
goto :EOF
:PCOKOB
@echo set IP=NONE
@echo for /f "Tokens=3* Delims=: " %%%%i in ('@ping -n 1 -w 250 %1^^^|find "TTL="'^) do set IP=%%%%i
@echo @echo %1,"%%IP%%"^>"%TEMP%\PCOK_%2.log"
@echo exit