You have introduced a new secondary DNS (Domain Name System) server online and notice that your monitoring software reports a significant increase in network traffic. Which TWO hosts on your network are likely to be causing the increased traffic and why?

a.
The caching and primary DNS servers, because the caching server is requesting zone transfers from the primary server.

b.
The secondary and primary DNS servers, because the secondary server is requesting zone transfers from the primary server.

c.
The root and primary DNS servers, because the primary server is requesting zone transfers from the root server.

d.
The Web server and primary DNS server, because the Web server is requesting zone transfers from the primary DNS server.