An IT administrator has installed new DNS name servers (Primary and Secondary), which are used to host the company MX records and resolve the web server's public address. In order to secure the zone…

Email spamming involves sending unsolicited bulk email and has no direct relationship to DNS zone transfer mechanisms or ACL configurations.

ACLs permit zone transfers based solely on the source IP address of the requesting server. An attacker can craft packets with a spoofed source IP matching the primary server's address, causing the secondary DNS server to accept a malicious or unauthorized zone transfer. This bypass is possible because ACLs alone provide no cryptographic verification of the sender's identity, unlike TSIG (Transaction Signature) which would authenticate the transfer.

Clickjacking is a UI redress attack that tricks users into clicking hidden elements in a browser, which is entirely unrelated to DNS server-to-server zone transfer security.

DNS replication is a description of the zone transfer process itself, not an attack vector, and does not represent a distinct threat that ACLs would or would not mitigate.