Recursive Server 101

	Ed Lewis
	edlewis@arin.net

Overview

	Recursive Service
	root server list
	localhost.
	0.0.127.in-addr.arpa.
	named.conf

Recursive Server

	Used to lookup data by applications
	Needs to know how to reach top of DNS
	Also should stop some queries
		localhost, 127.0.0.1
	Files
		named.conf
		root.hints
		localhost zone
		0.0.127.in-addr.arpa zone
	We'll do named.conf last

Root Server List

	List of the 13 root server records
	Where to get it
		ftp rs.internic.net
		anonymous login
		cd domain
		get one of these files (they are [nearly] the same)
			db.cache
			named.root
			named.cache

What it looks like

	;       This file holds the information on root name servers needed to
	;       initialize cache of Internet domain name servers
	;       (e.g. reference this file in the "cache  .  <file>"
	;       configuration file of BIND domain name servers).
	;
	;       This file is made available by InterNIC
	;       under anonymous FTP as
	;           file                /domain/named.cache
	;           on server           FTP.INTERNIC.NET
	;
	;       last update:    Nov 5, 2002
	;       related version of root zone:   2002110501
	;
	;
	; formerly NS.INTERNIC.NET
	;
	.                        3600000  IN  NS    A.ROOT-SERVERS.NET.
	A.ROOT-SERVERS.NET.      3600000      A     198.41.0.4
	;
	.................
	; housed in Japan, operated by WIDE
	;
	.                        3600000      NS    M.ROOT-SERVERS.NET.
	M.ROOT-SERVERS.NET.      3600000      A     202.12.27.33
	; End of File

What You Do To This File

	Nothing
	You will include it in named.conf
	In real networks, don't change it
		But for learning, we will change it

localhost

	Loopback name in operating systems
	Means 127.0.0.1
	Queries for this shouldn't use recursion
	So we will configure a file to define the localhost. zone
		Note the "."

localhost file

	$ORIGIN localhost.
	$TTL 86400
	@        IN     SOA localhost. root.localhost. (
	1  ; serial
	1800  ; refresh
	900  ; retry
	69120  ; expire
	1080  ; negative cache ttl
	)
	NS localhost.
	A 127.0.0.1

Reverse for localhost

	Since we want "localhost -> 127.0.0.1" we want to have "127.0.0.1 -> 127.0.0.1"
	We need a zone called 0.0.127.in-addr.arpa

0.0.127.in-addr.arpa file

	$ORIGIN 0.0.127.in-addr.arpa.
	$TTL 86400
	@        IN     SOA localhost. root.localhost. (
	1  ; serial
	1800  ; refresh
	900  ; retry
	69120  ; expire
	1080  ; negative cache ttl
	)
	NS  localhost.
	1               PTR localhost.

Assembling the files

	Here's my directory:
		[~/DNS/apricot2003/recursive] edlewis% ls
		0.0.127.in-addr.arpa.   localhost.              named.root
	The directory name and file names will be in named.conf
	Now I create a named.conf file in the same directory...

named.conf

	options {
	directory "/Users/edlewis/DNS/apricot2003/recursive";
	pid-file "/Users/edlewis/DNS/apricot2003/recursive/n.pid";
	recursion yes;
	};
	zone "." {
	type hint;
	file "named.root";
	};
	zone "localhost." {
	type master;
	file "localhost.";
	};
	zone "0.0.127.in-addr.arpa." {
	type master;
	file "0.0.127.in-addr.arpa.";
	};

Running the server

	From the directory
		sudo named -c named.conf

Testing the server

	Just to show it is alive
		dig @127.0.0.1 www.arin.net
		; <<>> DiG 9.2.2rc1 <<>> @127.0.0.1 www.arin.net
		;; global options:  printcmd
		;; Got answer:
		;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 16580
		;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 10, ADDITIONAL: 0
		;; QUESTION SECTION:
		;www.arin.net.                  IN      A
		;; ANSWER SECTION:
		www.arin.net.           10800   IN      A       192.149.252.17
		www.arin.net.           10800   IN      A       192.149.252.16
		;; AUTHORITY SECTION:
		arin.net.               10800   IN      NS      arrowroot.arin.net.
		(and so on)
		;; Query time: 3066 msec
		;; SERVER: 127.0.0.1#53(127.0.0.1)
		;; WHEN: Wed Feb 19 11:07:05 2003
		;; MSG SIZE  rcvd: 251

Congratulations - Your First Server!

	It's just the beginning...

Questions?