% for i in seq 1 10; do curl -v 'http://a.tile.opencyclemap.org/landscape/14/10158/6017.png' > /dev/null 2>&1 | grep Cache-Control; done
< Cache-Control: max-age=45952
< Cache-Control: max-age=46909
< Cache-Control: max-age=50170
< Cache-Control: max-age=48410
< Cache-Control: max-age=51360
< Cache-Control: max-age=49457
< Cache-Control: max-age=43234
< Cache-Control: max-age=46239
< Cache-Control: max-age=45978
< Cache-Control: max-age=47474