you can use the command:
xdpyinfo|less
to get your X-server version:

name of display:    :0.0
version number:    11.0
vendor string:    The X.Org Foundation
vendor release number:    11604000
X.Org version: 1.16.4
maximum request size:  16777212 bytes
motion buffer size:  256
bitmap unit, bit order, padding:    32, LSBFirst, 32
image byte order:    LSBFirst
number of supported pixmap formats:    7
supported pixmap formats:
    depth 1, bits_per_pixel 1, scanline_pad 32
    depth 4, bits_per_pixel 8, scanline_pad 32
    depth 8, bits_per_pixel 8, scanline_pad 32
    depth 15, bits_per_pixel 16, scanline_pad 32
    depth 16, bits_per_pixel 16, scanline_pad 32
    depth 24, bits_per_pixel 32, scanline_pad 32
    depth 32, bits_per_pixel 32, scanline_pad 32
keycode range:    minimum 8, maximum 255
focus:  window 0x2400021, revert to Parent
number of extensions:    29
    BIG-REQUESTS
    Composite
    DAMAGE
    DOUBLE-BUFFER
    DPMS
    DRI2
    DRI3
    GLX

example data from Hyper-V VM: debian8.xdpyinfo.example.output.txt

manpage:

xdpyinfo.man.txt

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