What is an AXFR request?

What is an AXFR request?

AXFR is a protocol for “zone transfers” for replication of DNS data across multiple DNS servers. Unlike normal DNS queries that require the user to know some DNS information ahead of time, AXFR queries reveal resource records including subdomain names [1] .

What does AXFR stand for?


Acronym Definition
AXFR All Zone Transfer (computer infrastructure)
AXFR Authoritative Transfer (Internet Infrastructure)
AXFR Asynchronous Full Transfer Zone (DNS request)
AXFR DNS (Domain Name System) Zone Transfer Protocol (Internet infrastructure)

What is the difference between the two zone transfer types AXFR and IXFR?

The current full zone transfer mechanism (AXFR) is not an efficient means to propagate changes to a small part of a zone, as it transfers the entire zone file. Incremental transfer (IXFR) as proposed is a more efficient mechanism, as it transfers only the changed portion(s) of a zone.

What are the three types of zone transfers?

There are three types of zone transfer to consider:

  • Full zone transfer.
  • Incremental zone transfer.
  • AD replication.

What is the purpose of zone transfer?

Zone transfers are typically used to replicate DNS data across a number of DNS servers or to back up DNS files. A user or server will perform a specific zone transfer request from a name server.

What port does AXFR use?

TCP port 53
It connects to an AXFR server on TCP port 53.

Which port does a DNS zone transfer use?

TCP Port 53
Explanation. DNS Zone transfers are performed over TCP Port 53. UDP Port 53 performs domain name resolution.

How do I transfer a DNS zone?

In the DNS Manager, right-click the name of the DNS zone and click Properties. On the Zone Transfers tab, click Allow zone transfer. Select Only to the following servers. Click Edit, then in the IP addresses of the secondary servers list, enter the IP addresses of the servers you wish to specify.

How do DNS zone transfers work?

Zone transfer is the process of copying the contents of the zone file on a primary DNS server to a secondary DNS server. Using zone transfer provides fault tolerance by synchronizing the zone file in a primary DNS server with the zone file in a secondary DNS server.

What triggers a zone transfer?

When a secondary DNS server starts up, it initiates a zone transfer from the master DNS server. It also checks periodically for updates on the master DNS server. If changes have been made, it initiates a zone transfer.

Why do we require a zone?

A DNS zone is also an administrative function, allowing for granular control of DNS components, such as authoritative name servers. in simple language,Zone consists of resource records and we require zone for representing sites.

How do you stop a zone transfer?

The simplest way to secure zone transfers is to restrict AXFR requests to trusted IP addresses. You can do it in your DNS server configuration or on your firewall. You can additionally use transaction signatures. Learn how to use transaction signatures in the BIND DNS server.

An AXFR request is a DNS query packet. Here are its contents: A two-byte query ID selected by the client. Byte \\000 (meaning: query, opcode 0, not authoritative, not truncated, recursion not desired).

When does the AXFR request skip in the SOA response?

BIND 9 skips the AXFR request unless the serial number in the SOA response minus the serial number in the zone on disk, modulo 2^32, is between 1 and 2^31-1 inclusive. This rule is specified in RFC 1982.

Should the AXFR client restart the connection after a disruption?

If the disruption was a spurious event, attempting to restart the connection would be proper. If the disruption was caused by a failure that proved to be persistent, the AXFR client would be wise not to spend too many resources trying to rebuild the connection.

How many RRS should an AXFR response message contain?

Each AXFR response message SHOULD contain a sufficient number of RRs to reasonably amortize the per-message overhead, up to the largest number that will fit within a DNS message (taking the required content of the other sections into account, as described below). Lewis & Hoenes Standards Track [Page 11]