Internally, this is achieved with a setting called "other_countries"
which I set for these two German mirrors, as shown below; you can see
that they are also used as reserve mirror for many other countries -
most of Africa, Baltic states, and others.
mb list --other-countries | grep '\<il\>'
halifax.rwth-aachen.de dk,pl il,tr,vn
ao,bf,bi,bj,bv,cd,cf,cg,ci,cm,cv,dj,dz,eg,eh,er,et,ga,gh,gm,gn,gq,gw,hm,ke
,km,lr,ly,ma,mg,ml,mr,mu,mw,mz,ne,ng,re,rw,sc,sd,sh,sl,sn,so,st,td,tf,tg,t
n,tz,ug,yt,za,zm,zw a2 ge,kz,ru in
ftp5.gwdg.de dk,pl il,tr,vn
ao,bf,bi,bj,bv,cd,cf,cg,ci,cm,cv,dj,dz,eg,eh,er,et,ga,gh,gm,gn,gq,gw,hm,ke
,km,lr,ly,ma,mg,ml,mr,mu,mw,mz,ne,ng,re,rw,sc,sd,sh,sl,sn,so,st,td,tf,tg,t
n,tz,ug,yt,za,zm,zw a2 ge,kz,ru in
