Based on that log we wish to produce the following output

  @echo off & setlocal enableextensions enabledelayedexpansion
  ::
  :: Define location of a temporary folder and auxiliary files
  set temp_=%temp%
  if defined mytemp set temp_=%mytemp%
  set TempFileForOneNslookupLine=%temp_%\ipnames1line.tmp
  set TempFileForOutput=%temp_%\ipnames2.tmp
  set TailOfTheOriginal=%temp_%\ipnamesTail.tmp
  ::
  :: Ensure a clean plate
  for %%f in ("%TempFileForOneNslookupLine%"
    "%TempFileForOutput%"
    "%TailOfTheOriginal%") do if exist %%f del %%f
  ::
  :: Is help required?
  set help_=
  if "%~1"=="" set help_=true
  if "%~1"=="?" set help_=true
  if "%~1"=="/?" set help_=true
  if defined help_ (call :DisplayHelp & goto :EOF)
  ::
  :: Does the original log file exist?
  set OriginalLogFile=%~1
  if not exist "%OriginalLogFile%" (
    call :ProgTitle
    >con echo.
    >con echo File "%OriginalLogFile%" not found
    goto :EOF)
  ::
  :: Count the lines in the original log file
  call :CountLines "%OriginalLogFile%" lineCount
  for /f %%n in ("%lineCount%") do set lineCount=%%n
  ::
  :: Copy the entrire original log file or optionally get its tail
  if "%~2"=="" (
    copy "%OriginalLogFile%" "%TailOfTheOriginal%" > nul
    ) else (
    call :TypeTail "%OriginalLogFile%" %lineCount% %%2 %TailOfTheOriginal%)
  ::
  :: Do the resolving line by line
  for /f "tokens=1-3" %%a in ('type "%TailOfTheOriginal%"') do (
    call :FuncRightJustify15 %%c ipnum_
    nslookup %%c|find "Name: " > "%TempFileForOneNslookupLine%"
    call :GetOneIPname "%TempFileForOneNslookupLine%" ipname_
    echo %%a %%b !ipnum_! !ipname_!>> "%TempFileForOutput%")
  ::
  :: Present the outcome
  cls
  call :ProgTitle
  >con echo.
  if "%~2"=="" echo "%OriginalLogFile%" %lineCount% lines
  if not "%~2"=="" echo "%OriginalLogFile%" last %~2 of %lineCount% lines
  type "%TempFileForOutput%"
  ::
  :: Clean up
  :_cleanup
  for %%f in ("%TempFileForOneNslookupLine%"
    "%TempFileForOutput%"
    "%TailOfTheOriginal%") do if exist %%f del %%f
  endlocal & goto :EOF

  :ProgTitle
  >con echo +----------------------------------------------------+
  >con echo ^¦ IPNAMES.CMD Get the names for a list of IP numbers ^¦
  >con echo ^¦ By Prof. Timo Salmi, last modified Mon 1-Feb-2010  ^¦
  >con echo +----------------------------------------------------+
  endlocal & goto :EOF

  :DisplayHelp
  call :ProgTitle
  >con echo.
  >con echo Usage: IPNAMES [InputLogFileName] [OnlyNumberOfLinesFromTheEnd]
  endlocal & goto :EOF

  :CountLines
  rem Return the number of non-blank lines of file %1
  setlocal enableextensions
    set lineCount=
    for /f %%n in ('type %1') do set /a lineCount+=1
  endlocal & set %2=%lineCount% & goto :EOF

  :TypeTail
  rem Output to file %%4 the last %3 lines of file %1 which is of length %2
  setlocal enableextensions enabledelayedexpansion
    set lineCount=
    set /a x_=%2-%3
    for /f "tokens=*" %%a in ('type %1') do (
      set /a lineCount+=1
      if !lineCount! GTR %x_% echo %%a) >> %4
    goto :EOF

  :FuncRightJustify15
  setlocal enableextensions
    set str_=               %1
    set str_=%str_:~-15%
  endlocal & set "%2=%str_%" & goto :EOF

  :GetOneIPname
  setlocal enableextensions
    set return_=UnKnown
    for /f "tokens=2" %%a in ('type %1') do set return_=%%a
  endlocal & set "%2=%return_%" & goto :EOF