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Returns all records of all types known to the name server. If the name server does not have any information on the name, the request will be forwarded on. The records returned may not be complete. For example, if there is both an A and an MX for a name, but the name server has only the A record cached, only the A record will be returned.
Decomposition of the quad-dotted IPv4 address representation to its binary value. IPv4 uses 32-bit addresses which limits the address space to 4 294 967 296 (2 32) addresses. IPv4 reserves special address blocks for private networks (2 24 + 2 20 + 2 16 ≈ 18 million addresses) and multicast addresses (2 28 ≈ 268 million addresses).
A DNS name server is a server that stores the DNS records for a domain; a DNS name server responds with answers to queries against its database. The most common types of records stored in the DNS database are for start of authority ( SOA ), IP addresses ( A and AAAA ), SMTP mail exchangers (MX), name servers (NS), pointers for reverse DNS ...
Users type in domain names, such as example.org, which the computer's DNS software looks up in the DNS databases to retrieve an IP address, and then hands off that address to the protocol stack for further communications. [5] Looking up an address using DNS requires the IP address of the DNS server to be known.
The addition of IPv6 addresses for the root name servers requires more than 512 bytes, which is facilitated by the EDNS0 extension to the DNS standard. [ 8 ] This does not mean that there are only 13 physical servers; each operator uses redundant computer equipment to provide reliable service even if failure of hardware or software occurs.
A public IP address is a globally routable unicast IP address, meaning that the address is not an address reserved for use in private networks, such as those reserved by RFC 1918, or the various IPv6 address formats of local scope or site-local scope, for example for link-local addressing. Public IP addresses may be used for communication ...
In client–server applications, load balancers forward client requests to a set of server computers to manage the workload of each server. Network address translation may be used to map a representative IP address of the server cluster to specific hosts that service the request. [11] [12] [13] [14]
It is important to note that this is the reverse order to the usual dotted-decimal convention for writing IPv4 addresses in textual form. For example, to do a reverse lookup of the IP address 8.8.4.4 the PTR record for the domain name 4.4.8.8.in-addr.arpa would be looked up, and found to point to dns.google.