Usage with m31:http://gaia.esac.esa.int/gost/GostServlet?name=m31, default VizieR name resolver. To change it, add service code: &service=code, integer code such as:
Use VizieR (The VizieR service at CDS), add &service=1
Use Simbad (The SIMBAD Astronomical Database at the Centre de Données astronomiques de Strasbourg (CDS).), add &service=2
Use Ned (The NASA/IPAC ExtraGalactic Database at the California Institute of Technology (CalTech).), add &service=3

Usage with ra,dec coordinates in degrees: http://gaia.esac.esa.int/gost/GostServlet?ra=20.0&dec=45.0
Just resolve name (ra,dec in deg): http://gaia.esac.esa.int/gost/GostServlet?name=m31&service=1&resolve