Recursive DNS resolution queries & & iterations of nslookup tool
Domain Name System (DNS, Domain Name System) is a distributed database TCP / IP applications to provide conversion between domain names and IP addresses. When, in some applications through the domain name system can use easy-to-remember domain name, the DNS server in the network to resolve the name to the correct IP address
Important name:
A record:
parsing is a host domain name corresponding ipv4 address.
NS record:
analytic is a sub-domain names under a domain name which can be resolved by the domain name server.
MX records:
parsing mail sub-domain names under a domain name which can be resolved by the domain name server.
CNAME record:
resolve a host of other domain names, alias record.
PTR record:
reverse analysis, parse out the domain name from the IP address. Little use.
TTL value:
stands for "survival time (Time To Live)", it represents a simple caching DNS record time on the DNS server.
nslookup tool
1, recursive query
recursive query is a type of DNS server query mode, in this mode the receiving DNS server to the client request, must return an accurate result of the client query.
If the DNS server queries DNS information is not stored locally, then the server will ask other servers, and submit query results returned to the client.
Query as an example www.google.com/www.baidu.com
2, iterative query
DNS server query to another iterative query, the DNS server will provide DNS server addresses to resolve the query request to the client, when the client sends when a query request, the DNS server does not respond directly to query results, but to tell the client to another DNS server address, the client again submit this request to the DNS server, followed by cycle until the return query results.
Queries www.baidu.com for example
# using 114.114.114.114 as a direct result of the analysis.
