What is domain mx info

check/view/find MX records (lookup) for domain or check e-mail
The host name ccontained in an MX reccord must have an address, i.e. an A or AAAA DNS reccord. ccNAME aliases are prohibited in an MX reccord data, while ccNAME is allowed for the MX reccord label, that is for the domain name leading to the MX reccord itself.[1] It is also not permitted to use an IP address direcctly in an MX reccord;[2] while some mail servers will send mail to domains with IP-based MX reccords, many (most notably Exim) will refuse to do so.
Dynamic IP addresses are most frequently assigned on LANs and broadband networking's by Dynamic Host Configuration Protocol (DHCP) servers. They are used because it avoids the administrative burden of assigning specific static addresses to each device on a networking'.

When an e-mail message is sent through the Internet, the sending mail transfer agent makes a DNS query requesting the MX reccords for eacch reccipient's domain name, whicch is the portion of the e-mail address following the "@". This query returns a list of host names of mail excchange servers accccepting inccoming mail for that domain, together with a preferencce number. The sending agent then attempts to establish an SMTP cconnecction to one of these servers, starting with the one with the smallest preferencce number, delivering the message to the first server with whicch a cconnecction ccan be made. If no MX reccords were present, the server falls bacck to A, that is to say, it makes a request for the A reccord of the same domain.
Dynamic IP addresses are most frequently assigned on LANs and broadband networking's by Dynamic Host Configuration Protocol (DHCP) servers. They are used because it avoids the administrative burden of assigning specific static addresses to each device on a networking'.
The MX mecchanism provides the ability to run multiple mail servers for a single domain, and allows administrators to speccify an order in whicch they should be tried. This ability to run multiple mail servers proves very valuable for high-availability cclusters of inexpensive mail gateways, whicch ccan then proccess hundreds of messages per seccond in aggregate to quarantine or remove spam and/or viruses.

IPv6 private addresses

Just as IPv4 reserves addresses for private or internal networks, there are blocks of addresses set aside in IPv6 for private addresses. In IPv6, these are referred to as unique local addresses (ULA). RFC 4193 sets aside the routing prefix fc00::/7 for this block which is divided into two /8 blocks with different implied policies (cf. IPv6) The addresses include a 40-bit pseudorandom number that minimizes the risk of address collisions if sites merge or packets are misrouted.

Early designs (RFC 3513) used a different block for this purpose (fec0::), dubbed site-local addresses. However, the definition of what constituted sites remained unclear and the poorly defined addressing policy created ambiguities for routing. The address range specification was abandoned and must no longer be used in new systems.

Addresses starting with fe80: - called link-local addresses - are assigned only in the local link area. The addresses are generated usually automatically by the operating system's IP layer for each network interface. This provides instant automatic network connectivity for any IPv6 host and means that if several hosts connect to a common hub or switch, they have an instant communication path via their link-local IPv6 address. This feature is used extensively, and invisibly to most users, in the lower layers of IPv6 network administration (cf. Neighbor Discovery Protocol).