Zone transfer: What is it?
Duplicating DNS records from the Primary DNS zone to the Secondary DNS zone is a procedure known as zone transfer. You can create several copies of your DNS records on other name servers in this manner. By executing the transfer, you will guarantee improved availability in the event that one of the name servers goes down. Additionally, if you run a global website with users from all over the world and different points of presence (PoPs), you will ensure faster DNS resolution.
What are Primary and Secondary DNS zones?
Different DNS zone transfers
You can transfer a DNS zone between name servers in one of two ways:
- Full zone transfer (AXFR). This is used to transfer all DNS records from the primary name server to a different name server (Secondary). If the Secondary hasn’t been updated in a while and you want to ensure it is, you can utilize it. Copying the data to a newly deployed name server without any prior data is another reason to conduct a full zone transfer.
- Incremental zone transfer (IXFR). This one is used to send updates to the Secondary name servers solely for newly generated, changed, or deleted DNS records from the Primary name server. You can use it to update only the changes while using minimal bandwidth. A partial zone file. Once you have already configured all of the Secondary name servers, it is more beneficial to use.
Is DNS zone transfer safety?
The security risks associated with DNS zone transfers can be readily mitigated by properly configuring the DNS software. A whole DNS zone’s worth of data could include sensitive information. DNS records aren’t susceptible on their own, but if a malicious party manages to get a hold of the whole DNS zone for a domain, they might have access to a complete list of all hosts in that domain. That makes it much simpler for hackers to do their work. If the name server is promiscuous and allows anyone to do a zone transfer, a computer hacker does not require any special equipment or access to obtain an entire DNS zone.
Of course, DNS zone transfers are a crucial and vital component of how DNS functions and cannot be fully disabled. However, DNS zone transfers must only be permitted between DNS servers and clients who truly want them. Only interdependent DNS servers typically require zone transfers. By using DNS keys and even encrypted DNS payloads, zone transfers can gain an extra layer of security.
If a cybercrime activity can transfer a DNS zone, it can conduct a Denial of Service (DoS) attack against the DNS servers for that zone by overloading them with numerous requests. However, this is substantially resolved by employing encryption and restricting access to perform DNS zone transfers.
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​Conclusion
The procedure by which DNS copies zone files or specific DNS entries from a Primary name server to one or more Secondary name servers is known as DNS zone transfer. Knowing and understanding if you will administrate the Domain Name System is critical.