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How to test DNS server for host Resolution

The Domain Name System (DNS) is a standard technology for managing the names of Web sites and other Internet domains. DNS is an Internet service that translates domain names into IP addresses. Because domain names (example - are alphabetic, they're easier to remember. The Internet however, is really based on IP addresses. Every time you use a domain name, therefore, a DNS service must translate the name into the corresponding IP address. For example, the domain name might translate to

The DNS system is, in fact, its own network. If one DNS server doesn't know how to translate a particular domain name, it asks another one, and so on, until the correct IP address is returned.

There are a number of commands you can use do test the DNS server resolution.

The Host Command
host is a simple utility for performing DNS lookups. It is normally used to convert names to IP addresses and vice versa. When no arguments or options are given, host prints a short summary of its command line arguments and options.
# host has address
To perform a reverse lookup
# host domain name pointer
As you can see, the forward and reverse entries don't match. The reverse entry matches the entry of the ISP.

The nslookup Command
Nslookup is a program to query Internet domain name servers. Nslookup has two modes: interactive and non-interactive. Interactive mode allows the user to query name servers for information about various hosts and domains or to print a list of hosts in a domain. Non-interactive mode is used to print just the name and requested information for a host or domain

Non-authoritative answer:  canonical name =
To perform a reverse lookup

Non-authoritative answer:     name =
dig (domain information groper) is a flexible tool for interrogating DNS name servers. It performs DNS lookups and displays the answers that are returned from the name server(s) that were queried. Most DNS administrators use dig to troubleshoot DNS problems because of its flexibility, ease of use and clarity of output. Other lookup tools tend to have less functionality than dig.
# dig

; <<>> DiG 9.5.0-P2 <<>>
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 22795
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 0

;                        IN      A

;; ANSWER SECTION:         85097   IN      CNAME       259     IN      A

;; Query time: 1 msec
;; WHEN: Mon Jan 24 16:33:29 2011
;; MSG SIZE  rcvd: 68

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