DNS Foundation II

DNS Foundation II

Danbo Time: 2015-7-26

recursive query;
iterative query;

Forward parsing and inverse parsing;

Each correspondence we call: Record, according to the function of record, we are divided into the type of record.
Converts the hostname to an IP address, which we call a (address) record;
To convert an IP address to a hostname, we call it a PTR (Pointer) pointer record.
Both forward and reverse sets of databases must be stored separately.

SOA (start of authority, start authorization) record: Authorizes this zone's primary DNS server, domain name Administrator's email address and so on.
NS: The domain name server used in the region.
MX (mail eXchanger, email exchanger): When we send email to: [email protected], @ After gmail.com is a domain, the domain below must have the server responsible for sending and receiving mail (mail.gmail.com), and how does our host know where the mail server is located? This is the role of MX: The list of message transfer agents (MTA, message Transfer Agents) that directs the domain name to the domain name, and the list has a priority (priority,0-99 indicates that the smaller the number, the higher the priority).
CNAME (Canonical name, canonical name also called Alias Record). Note x CNAME y: At this point x is the alias, that is, the canonical name of X is Y.

The forward parsing DNS is load balanced and returns an IP address;
The reverse resolution, although also load balanced, returns all the corresponding FQDNs (full name domains) back to the requestor, but can also be set to return all FQDNs. The purpose of the reverse parsing is to verify that the resolved IP is correct, which is used on the mail server

Zone (Zone) and domains (domain)
We can understand this: a domain is a logical concept, and a region is a physical concept.
For example baidu.com we can interpret it as a domain, while there are two zones on the local NS server, one is the positive zone, the reverse zone, the area is artificial to define a domain subdomain (region), and this subdomain (region) by a file to manage, And it is divided into forward area and reverse region. However, domains and regions do not have a relationship with whom.

Subdomain Authorization (delegation): For example, Baidu.com is divided into: tech.baidu.com and Mark.baidu.com, the organization of the administrative domain can further divide the domain into subdomains. Each subdomain can be delegated to other organizations to manage, which means that these authorized organizations are responsible for maintaining all the data in the subdomain. They are free to change the data in the domain and even further divide the subdomain into more subdomains, which are then delegated to other organizations for administration. The parent domain simply retains a pointer to the data source of the subdomain so that the parent domain can lead the query to that place.

Primary DNS and secondary DNS servers, and when we define the RR for DNS only on the primary DNS server and rely on the TCP synchronization database with the service DNS, this process is called zone transfer.

Cache name servers and forwarding servers, cache name servers: Store the information it receives, and then make it available to other users for queries until the information expires. It does not have any configuration information for the local authorization domain in the configuration. Forwarding server: A cache server itself cannot perform a full recursive query. Instead, it can forward some or all of the unsatisfied queries from the cache to other cache servers, typically referred to as a forwarding server.

Configuration of the DNS server:
Domain Name: application

DNS Foundation II