krishnamurthydasari/Master-Slave DNS Setup in EC2

## Master-Slave DNS Setup in EC2
For this setup:

	DNS Master Server	172.31.88.75
	DNS Slave Server	172.31.93.71
	Host1			172.31.83.52
	Host2			172.31.88.91

	** Configured only fws zone. Reverse zone setup not tested.
	** Reference : https://www.tecmint.com/setup-master-slave-dns-server-in-centos/

DNS Master Setup:
=================

Installing Bind:

	yum install bind bind-utils bind-chroot

Configuring Bind:

	vi /etc/named.conf

		options {
		.
		.

		listen-on port 53 { 127.0.0.1; 172.31.88.75; };  # Add Master DNS Server IP
		#listen-on-v6 port 53 { ::1; }; # Comment ipv6 support
		allow-query     { localhost; any; }; # subnet range where my hosts are allowed to query our DNS. "any" will allow query requests from any host
		recursion yes;  # This will allow DNS server to fetch root servers if record is not available.
		allow-transfer     { localhost; 172.31.93.71; };  # Here we need to our Slave DNS server IP. This setting will be there in master DNS server
		.
		.
		}
		.
		.

		## Define our forward & reverse Zone file here for tecmintlocal.com.

		zone "example.com" IN {
			type master;
			file "zones/example.com.fwd.zone";
			allow-update { none; };
		};

		zone "0.168.192.in-addr.arpa" IN {
			type master;
			file "zones/example.com.rev.zone";
			allow-update { none; };
		};
		#####
		.
		.

	Following are the explanation of each configuration we used in above file.

	listen-on port 53 – This is used for the DNS to listen in available interfaces.
	Master DNS – Define, your Master DNS IP address to listen the query.
	Slave DNS – Define your Slave DNS, which is used to sync our zone information to resolve the hosts from Master.
	recursion no – If its set to yes, recursive queries will make the server into DDOS attack.
	Zone Name – Define your Zone name here defined as tecminlocal.com.
	type master – As this system was configured for a master server, for upcoming slave server this will be slave.
	example.com.fwd.zone – This file have the host information for this zone.
	allow-update none – If none will set. it won’t use Dynamic DNS (DDNS).

Configuring Zone files:

	cp /var/named/named.localhost /var/named/example.com.fwd.zone
	cp /var/named/named.loopback /var/named/example.com.rev.zone

	vi /var/named/example.com.fwd.zone

		$TTL 1D
		@       IN SOA  ns1.example.com. root.example.com. (
												3       ; serial
												1D      ; refresh
												1H      ; retry
												1W      ; expire
												3H )    ; minimum

		@       IN      NS      ns1.example.com.
		@       IN      NS      ns2.example.com.

		ns1     IN      A       172.31.88.75
		ns2     IN      A       172.31.93.71
		host1   IN      A       172.31.83.52
		host2   IN      A       172.31.88.91

	vi /var/named/example.com.rev.zone

		$TTL 1D
		@       IN SOA  ns1.example.com. root.example.com. (
												3       ; serial
												1D      ; refresh
												1H      ; retry
												1W      ; expire
												3H )    ; minimum

		@       IN      NS      ns1.example.com.
		@       IN      NS      ns2.example.com.

		ns1     IN      A       172.31.88.75
		ns2     IN      A       172.31.93.71
		210     IN      PTR     host1.example.com.
		220     IN      PTR     host2.example.com

	#chgrp named /var/named/example.com.fwd.zone
	#chgrp named /var/named/example.com.rev.zone

Test Configuration:

	#named-checkconf /etc/named.conf
	#named-checkzone example.com /var/named/example.com.fwd.zone
	#named-checkzone example.com /var/named/example.com.rev.zone

Start Service:

	#service named start
	#chkconfig named on
	#chkconfig --list named


Client Setup:
=============

	Edit /etc/resolv.conf file and update DNS server IPs

Test DNS:

	[root@ip-172-31-83-52 ~]# nslookup host1.example.com
	Server:         172.31.88.75
	Address:        172.31.88.75#53

	Name:   host1.example.com
	Address: 172.31.83.52

	[root@ip-172-31-83-52 ~]# dig host1.example.com

	; <<>> DiG 9.8.2rc1-RedHat-9.8.2-0.62.rc1.56.amzn1 <<>> host1.example.com
	;; global options: +cmd
	;; Got answer:
	;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 21700
	;; flags: qr aa rd; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 2
	;; WARNING: recursion requested but not available

	;; QUESTION SECTION:
	;host1.example.com.             IN      A

	;; ANSWER SECTION:
	host1.example.com.      86400   IN      A       172.31.83.52

	;; AUTHORITY SECTION:
	example.com.            86400   IN      NS      ns1.example.com.
	example.com.            86400   IN      NS      ns2.example.com.

	;; ADDITIONAL SECTION:
	ns1.example.com.        86400   IN      A       172.31.88.75
	ns2.example.com.        86400   IN      A       172.31.93.71

	;; Query time: 1 msec
	;; SERVER: 172.31.88.75#53(172.31.88.75)
	;; WHEN: Wed Jan 31 07:24:27 2018
	;; MSG SIZE  rcvd: 119

	[root@ip-172-31-83-52 ~]#

DNS Slave Setup:
================

Installing Bind:

	yum install bind bind-utils bind-chroot

Configuring Bind:

	vi /etc/named.conf

		options {
		.
		.

		listen-on port 53 { 127.0.0.1; 172.31.93.71; };  # Add Slave DNS Server IP
		#listen-on-v6 port 53 { ::1; }; # Comment ipv6 support
		allow-query     { localhost; any; }; # subnet range where my hosts are allowed to query our DNS. "any" will allow query requests from any host
		recursion yes;  # This will allow DNS server to fetch root servers if record is not available.
		.		.
		.
		}
		.
		.
		## Define our slave forward and reverse zone, Zone files are replicated from master.
		zone "example.com" IN {
			type slave;
			file "slaves/example.fwd.zone";
			masters { 172.31.88.75; };
		};
		zone "0.168.192.in-addr.arpa" IN {
			type slave;
			file "slaves/example.com.rev.zone";
			masters { 172.31.88.75; };
		};

Test Configuration:

	#named-checkconf /etc/named.conf

Start Service:

	#service named start
	#chkconfig named on
	#chkconfig --list named

**No need to create zone files on slave machine. when you start named service, files will automatically get synced from Master DNS server.
**Test nsloop by stopping DNS service on master. you should get response from slave automatically. and also stop service on slave and test. With dig command, note from where query is getting answered.
	For this setup:

	DNS Master Server 172.31.88.75
	DNS Slave Server 172.31.93.71
	Host1 172.31.83.52
	Host2 172.31.88.91

	** Configured only fws zone. Reverse zone setup not tested.
	** Reference : https://www.tecmint.com/setup-master-slave-dns-server-in-centos/

	DNS Master Setup:
	=================

	Installing Bind:

	yum install bind bind-utils bind-chroot

	Configuring Bind:

	vi /etc/named.conf

	options {
	.
	.

	listen-on port 53 { 127.0.0.1; 172.31.88.75; }; # Add Master DNS Server IP
	#listen-on-v6 port 53 { ::1; }; # Comment ipv6 support
	allow-query { localhost; any; }; # subnet range where my hosts are allowed to query our DNS. "any" will allow query requests from any host
	recursion yes; # This will allow DNS server to fetch root servers if record is not available.
	allow-transfer { localhost; 172.31.93.71; }; # Here we need to our Slave DNS server IP. This setting will be there in master DNS server
	.
	.
	}
	.
	.

	## Define our forward & reverse Zone file here for tecmintlocal.com.

	zone "example.com" IN {
	type master;
	file "zones/example.com.fwd.zone";
	allow-update { none; };
	};

	zone "0.168.192.in-addr.arpa" IN {
	type master;
	file "zones/example.com.rev.zone";
	allow-update { none; };
	};
	#####
	.
	.

	Following are the explanation of each configuration we used in above file.

	listen-on port 53 – This is used for the DNS to listen in available interfaces.
	Master DNS – Define, your Master DNS IP address to listen the query.
	Slave DNS – Define your Slave DNS, which is used to sync our zone information to resolve the hosts from Master.
	recursion no – If its set to yes, recursive queries will make the server into DDOS attack.
	Zone Name – Define your Zone name here defined as tecminlocal.com.
	type master – As this system was configured for a master server, for upcoming slave server this will be slave.
	example.com.fwd.zone – This file have the host information for this zone.
	allow-update none – If none will set. it won’t use Dynamic DNS (DDNS).

	Configuring Zone files:

	cp /var/named/named.localhost /var/named/example.com.fwd.zone
	cp /var/named/named.loopback /var/named/example.com.rev.zone

	vi /var/named/example.com.fwd.zone

	$TTL 1D
	@ IN SOA ns1.example.com. root.example.com. (
	3 ; serial
	1D ; refresh
	1H ; retry
	1W ; expire
	3H ) ; minimum

	@ IN NS ns1.example.com.
	@ IN NS ns2.example.com.

	ns1 IN A 172.31.88.75
	ns2 IN A 172.31.93.71
	host1 IN A 172.31.83.52
	host2 IN A 172.31.88.91

	vi /var/named/example.com.rev.zone

	$TTL 1D
	@ IN SOA ns1.example.com. root.example.com. (
	3 ; serial
	1D ; refresh
	1H ; retry
	1W ; expire
	3H ) ; minimum

	@ IN NS ns1.example.com.
	@ IN NS ns2.example.com.

	ns1 IN A 172.31.88.75
	ns2 IN A 172.31.93.71
	210 IN PTR host1.example.com.
	220 IN PTR host2.example.com

	#chgrp named /var/named/example.com.fwd.zone
	#chgrp named /var/named/example.com.rev.zone

	Test Configuration:

	#named-checkconf /etc/named.conf
	#named-checkzone example.com /var/named/example.com.fwd.zone
	#named-checkzone example.com /var/named/example.com.rev.zone

	Start Service:

	#service named start
	#chkconfig named on
	#chkconfig --list named


	Client Setup:
	=============

	Edit /etc/resolv.conf file and update DNS server IPs

	Test DNS:

	[root@ip-172-31-83-52 ~]# nslookup host1.example.com
	Server: 172.31.88.75
	Address: 172.31.88.75#53

	Name: host1.example.com
	Address: 172.31.83.52

	[root@ip-172-31-83-52 ~]# dig host1.example.com

	; <<>> DiG 9.8.2rc1-RedHat-9.8.2-0.62.rc1.56.amzn1 <<>> host1.example.com
	;; global options: +cmd
	;; Got answer:
	;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 21700
	;; flags: qr aa rd; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 2
	;; WARNING: recursion requested but not available

	;; QUESTION SECTION:
	;host1.example.com. IN A

	;; ANSWER SECTION:
	host1.example.com. 86400 IN A 172.31.83.52

	;; AUTHORITY SECTION:
	example.com. 86400 IN NS ns1.example.com.
	example.com. 86400 IN NS ns2.example.com.

	;; ADDITIONAL SECTION:
	ns1.example.com. 86400 IN A 172.31.88.75
	ns2.example.com. 86400 IN A 172.31.93.71

	;; Query time: 1 msec
	;; SERVER: 172.31.88.75#53(172.31.88.75)
	;; WHEN: Wed Jan 31 07:24:27 2018
	;; MSG SIZE rcvd: 119

	[root@ip-172-31-83-52 ~]#

	DNS Slave Setup:
	================

	Installing Bind:

	yum install bind bind-utils bind-chroot

	Configuring Bind:

	vi /etc/named.conf

	options {
	.
	.

	listen-on port 53 { 127.0.0.1; 172.31.93.71; }; # Add Slave DNS Server IP
	#listen-on-v6 port 53 { ::1; }; # Comment ipv6 support
	allow-query { localhost; any; }; # subnet range where my hosts are allowed to query our DNS. "any" will allow query requests from any host
	recursion yes; # This will allow DNS server to fetch root servers if record is not available.
	. .
	.
	}
	.
	.
	## Define our slave forward and reverse zone, Zone files are replicated from master.
	zone "example.com" IN {
	type slave;
	file "slaves/example.fwd.zone";
	masters { 172.31.88.75; };
	};
	zone "0.168.192.in-addr.arpa" IN {
	type slave;
	file "slaves/example.com.rev.zone";
	masters { 172.31.88.75; };
	};

	Test Configuration:

	#named-checkconf /etc/named.conf

	Start Service:

	#service named start
	#chkconfig named on
	#chkconfig --list named

	**No need to create zone files on slave machine. when you start named service, files will automatically get synced from Master DNS server.
	**Test nsloop by stopping DNS service on master. you should get response from slave automatically. and also stop service on slave and test. With dig command, note from where query is getting answered.