V-265983

Discussion

Authoritative name servers (especially primary name servers) must be configured with an allow-transfer access control substatement designating the list of hosts from which zone transfer requests can be accepted. These restrictions address the denial-of-service (DoS) threat and potential exploits from unrestricted dissemination of information about internal resources. Based on the need-to-know, the only name servers that need to refresh their zone files periodically are the secondary name servers. Zone transfer from primary name servers must be restricted to secondary name servers. The zone transfer must be completely disabled in the secondary name servers. The address match list argument for the allow-transfer substatement must consist of IP addresses of secondary name servers and stealth secondary name servers.

Check Content

If the BIG-IP is transferring zones from another non-BIG-IP DNS server perform the following.

From the BIG-IP GUI:
1. DNS.
2. Zones.
3. Zone List.
4. Click on the name of the Zone.
5. Verify "Zone Transfer Clients" >> "Active" column shows only the nameservers that are allowed to request zone transfers.

If the BIG-IP appliance is not configured to limit the secondary name servers from which an authoritative name server receives zone transfer requests, this is a finding.