DNS delegation of m.facbook.com updated: May 25, 2013 12:41:55 PM
Delegation
step
query
auth
servers
1
m.facbook.com.
.
(m,l,e,h,i,j,a,b,k,c,d,g,f).root-servers.net.
2
m.facbook.com.
com.
(g,k,h,f,b,i,j,l,a,d,m,e,c).gtld-servers.net.
3
m.facbook.com.
facbook.com.
(b,a).ns.facebook.com.
4
m.facebook.com.
com.
(j,g,h,e,m,i,c,l,d,a,b,k,f).gtld-servers.net.
5
m.facebook.com.
facebook.com.
(a,b).ns.facebook.com.
6
m.c10r.facebook.com.
facebook.com.
(a,b).ns.facebook.com.
7
m.c10r.facebook.com.
c10r.facebook.com.
(a,b).ns.c10r.facebook.com.
We pick m.root-servers.net, one of the 13 root servers (1), and ask it about m.facbook.com and learn that com is delegated to 13 name servers (2), so we ask g.gtld-servers.net where we learn that facbook.com is delegated to two name servers, including b.ns.facebook.com (3), so we ask that one where we see a CNAME from m.facbook.com to m.facebook.com, so we have to start all over again. We already know that j.gtld-servers.net is authoritative for com (4) and ask it about m.facebook.com and learn that facebook.com is delegated to two name servers (5), so we ask a.ns.facebook.com and see a second CNAME from m.facebook.com to m.c10r.facebook.com. We start over for the third time and we already know that a.ns.facebook.com is authoritative for facebook.com (6) and ask it about m.c10r.facebook.com and learn that c10r.facebook.com is delegated to two name servers (7), so we ask a.ns.c10r.facebook.com and get the following answer:
