This document discusses different types of DNS servers and their roles. It describes resolvers that take requests from applications and query caching nameservers, which may have the answer cached or query authoritative nameservers. It also mentions authoritative nameservers that provide answers for configured domain names and lists some alternative DNS server software like PowerDNS, BIND, and DNSTOP.

1. DNS Servers
Gaurav Chaturvedi
gaurav.c@directi.com

2. Application => Resolver => Caching NS => Auth NS
( i.e Web
Browser )

3. RESOLVER
Takes request from application, formats it into
UDP packet, sends to cache

4. CACHING NAMESERVER
Returns the answer if already known,
Otherwise searches for an authoritative server
which has the information.
Caches the result for future queries.

5. AUTHORITATIVE NAMESERVER
An authoritative name server is a name server
that gives answers in response to questions
asked about names in a zone.
An authoritative-only name server only returns
answers to queries about domain names that
have been specifically configured by the
administrator.

6. Caching NameServers
Where would you need them?
Directly on a workstation or server
In a Small Office / Home Office
On a corporate network

8. DNSCACHE
dnscache maintains a limited-size cache of DNS
information, 1 megabyte by default.
Unlike BIND (which keeps growing), discards
older cache entries.

9. Powerdns
Lots of Backends:-
MySQL, PostgreSQL, Oracle, DB2,
OpenDBX,SQLite, BIND, LDAP, geo, pipe, etc.
Install a Zone Editor :-
PowerAdmin
WebDNS
ZoneAdmin
A webpage detailing its own stats.

10. BIND
The most widely used DNS software on the
Internet.
Widely documented
Can be used as a Caching nameserver

11. DSC

12. DNSTOP
Queries: 452 new, 4888 total
Wed Jul 18 18:38:56 2012
Query Name
Count % cum%
-------------------------------------------------------
--------- ------ ------
l.google.com 111
2.3 2.3
1.nfps.bz 83

13. Reference
http://jpmens.net/2010/10/29/alternative-dns-
servers-the-book-as-pdf/