What type of DNS record is used for email?
mail exchange
A DNS ‘mail exchange’ (MX) record directs email to a mail server. The MX record indicates how email messages should be routed in accordance with the Simple Mail Transfer Protocol (SMTP, the standard protocol for all email).
What is AXFR record?
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] .
How do I prevent malicious DNS zone transfers?
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.
What do you mean by DNS zone transfers?
DNS zone transfer, also known as DNS query type AXFR, is a process by which a DNS server passes a copy of part of its database to another DNS server. The portion of the database that is replicated is known as a zone.
Is DNS important for email?
For proper configuration of a public facing mailserver for proper sending and receiving of mail, it is necessary to configure your public DNS. records so that other mailservers can find you to send mail to your users, and so that other mailservers will trust you to receive your mail.
What is an email DNS?
DNS stands for Domain Name System and is a protocol for exchanging data on the Internet. Imagine this process as similar to driving to a new destination using your sat nav. The DNS then translates the name into an IP address. An IP address is a series of numbers separated by stops (e.g. 185.54.
How many DNS records are there?
DNS servers store records. When a DNS query is sent by a device, that query gets a response from those records with the help of DNS servers and resolvers. There are eight records that you see again and again: A, AAAA, CNAME, PTR, NS, MX, SOA, and TXT. We’ll focus here on those.
What Axfr means?
Asynchronous Full Transfer Zone
AXFR. Asynchronous Full Transfer Zone (DNS request)
What problems can DNS cause?
If DNS isn’t working properly, you won’t be able to use web-connected services, such as your browser or email, despite your computer or router showing a working internet connection. The webpage may timeout, give you an error message, or even bring up a specific “DNS error” message.
What does Axfr stand for?
AXFR
| 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) |
Is a DNS zone transfer illegal?
In most countries, including the United States, it IS ILLEGAL to attempt unauthorized zone transfers.
What does an AXFR request do for DNS?
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] .
How is port 53 used in the AXFR protocol?
TCP port 53 is simultaneously used by normal (non-AXFR) DNS clients requesting data that did not fit through UDP. A non-AXFR DNS client tries all queries through UDP first; however, if a UDP DNS server sets the “TC” bit in its response, the DNS client tries the query again through TCP.
Are there any flaws in the AXFR protocol?
One of the flaws in the AXFR protocol is that it’s actually impossible for servers to follow this rule under all circumstances. AXFR clients will sometimes fail to pick up changes in a zone. For example, suppose a BIND 9 AXFR client receives a zone through AXFR, and then checks for changes later.
How does a BIND 9 AXFR client work?
A UDP-SOA AXFR client, such as the BIND 9 AXFR client, works as follows. It may send an SOA request to a DNS server on UDP port 53 and receive a response. It may then connect to an AXFR server on TCP port 53 at the same IP address, send an AXFR request, receive an AXFR response, and close the connection.