![ReversePrimary DNS for PTR type record ipv4
1. A primary DNS server is responsible for reading data related to the domain zone and respond to
Ip address of that Fully Qualified Domain Name (FQDN) and vice-versa means take Ip address
respond to Fully Qualified Domain Name (FQDN).
2. But here we have used PTR record so FQDN to Ip address.
3. Primary DNS is only One But Secondary can be multiple in numbers.
4. The connection between Client and Primary DNS is through 53/UDP port.
5. The connection between Primary DNS ans Secondary DNS is through 53/TCP port.
6. We can query for ip from primary DNS only means we can’t query from secondary DNS
7. The primary server is also responsible for communicating with the secondary server for
recovery purpose..
8. The process of a primary web server communicating with the secondary server is known as a
zone transfer, as zone data is being sent from a DNS server to another.
9. Each domain name is assigned to DNS servers for redundancy, and to simplify the process of
server administration. If a primary server already contains the zone data for a domain, this data
does not need to be replicated because the primary and secondary server continuously share
zone data.
➔ Creating Own Primary DNS on Linux using bind pakage For Rhel or CentOs
➔ Installing Software packages bind (it helps us create to primary dns)
[root@piyush Desktop]# yum install bind -y](https://image.slidesharecdn.com/2-180205205825/85/2-reverse-primarydns-using-bind-for-ptr-and-cname-record-ipv4-1-320.jpg)
![➔ To see the confriguration file bind
[root@piyush Desktop]# rpm -qc bind
/etc/logrotate.d/named
/etc/named.conf
/etc/named.iscdlv.key
/etc/named.rfc1912.zones
/etc/named.root.key
/etc/rndc.conf
/etc/rndc.key
/etc/sysconfig/named
/var/named/named.ca
/var/named/named.empty
/var/named/named.localhost
/var/named/named.loopback
➔ Now takes backup of named.conf file as named.conf.bak
➔ named.conf looks like this
➔ [root@piyush etc]# vim named.conf
➔ Now empty the content of file.
[root@piyush etc]# echo > named.conf
Now creating the Zone for a particular domain
[root@piyush etc]# vim named.conf
● In Image :-](https://image.slidesharecdn.com/2-180205205825/85/2-reverse-primarydns-using-bind-for-ptr-and-cname-record-ipv4-2-320.jpg)
![Note:- Ends every line in named.conf with “;”
options :- provides you option where to create zone file and Forwarder DNS
directory :- where you want to create your Zone File gives the path here
For every create Zone block
zone :- for creating zone for different Network having different Ip address Pool
"0.168.192.in-addr.arpa" :- Ip address Pool of network “192.168.0.” means write
Octet of Network in reverse order.
master :- is for Primary DNS
0.168.192.revdns :- Zone file Name (name can be any thing but for convenience use name
as Network address )
similarly create Zone for Network “100.100.10.”
➔ Now create the zone file (0.168.192.revdns and 10.100.100.revdns)
[root@piyush etc]# cd /var/named/
[root@piyush named]# ls
data dynamic named.ca named.empty named.localhost named.loopback slaves
➔ Firstly copy the content of named.localhost in the file 0.168.192.revdns and
10.100.100.revdns (Zone file)
[root@piyush named]# cat named.localhost](https://image.slidesharecdn.com/2-180205205825/85/2-reverse-primarydns-using-bind-for-ptr-and-cname-record-ipv4-3-320.jpg)
![[root@piyush named]# cp named.localhost 0.168.192.revdns
[root@piyush named]# cp named.localhost 10.100.100.revdns
➔ Make the owner and group of file to named
[root@piyush named]#chown named:named 0.168.192.revdns
[root@piyush named]#chown named:named 10.100.100.revdns
➔ Now editing the files according to the requirement
[root@piyush named]# vim 0.168.192.revdnss
● In image :-](https://image.slidesharecdn.com/2-180205205825/85/2-reverse-primarydns-using-bind-for-ptr-and-cname-record-ipv4-4-320.jpg)
![FQDN:= Fully Qualified Domain Name hostname.domainname.topleveldomain
hostname.subdomainname.domainname.topleveldomain
Note :-
If you writing FQDN them put “.” Dot at end otherwise if you wrinting only hostname
no need to put Dot at end.
Not necessary to write TTL
Entry Format:- RemainingOctetOfIpAddr TTL IN Record_Type FQDN
55 :- remaining Octet of Ip Address means here last octet or host.
IN :- Internet
abc.piyush.com. :- FQDN
RECORD_TYPE
PTR :- For Ip address to FQDN conversion
CNAME :- Canonical name means here zxc.piyush.com. Points to
same Ip addresses 192.168.0.55 and 192.168.0.54
➔ Similarly for Network 100.100.10
[root@piyush named]# vim 10.100.100.revdnss
● In image :-](https://image.slidesharecdn.com/2-180205205825/85/2-reverse-primarydns-using-bind-for-ptr-and-cname-record-ipv4-5-320.jpg)
![Note:-
If firewall is running add dns to firewalld service or flush the firewalld as you wish
➔ Now restart the service if no error in syntax , the service get restart without error
[root@piyush Desktop]# systemctl restart named
[root@piyush Desktop]# systemctl enable --now named
➔ Now move to another pc or client to check
➔ Firstly adding nameserver as ip of DNS server.
root@piyush Desktop]#vim /etc/resolv.conf
Now do query :-](https://image.slidesharecdn.com/2-180205205825/85/2-reverse-primarydns-using-bind-for-ptr-and-cname-record-ipv4-6-320.jpg)
2. reverse primarydns using bind for ptr and cname record ipv4
- 1. ReversePrimary DNS for PTR type record ipv4 1. A primary DNS server is responsible for reading data related to the domain zone and respond to Ip address of that Fully Qualified Domain Name (FQDN) and vice-versa means take Ip address respond to Fully Qualified Domain Name (FQDN). 2. But here we have used PTR record so FQDN to Ip address. 3. Primary DNS is only One But Secondary can be multiple in numbers. 4. The connection between Client and Primary DNS is through 53/UDP port. 5. The connection between Primary DNS ans Secondary DNS is through 53/TCP port. 6. We can query for ip from primary DNS only means we can’t query from secondary DNS 7. The primary server is also responsible for communicating with the secondary server for recovery purpose.. 8. The process of a primary web server communicating with the secondary server is known as a zone transfer, as zone data is being sent from a DNS server to another. 9. Each domain name is assigned to DNS servers for redundancy, and to simplify the process of server administration. If a primary server already contains the zone data for a domain, this data does not need to be replicated because the primary and secondary server continuously share zone data. ➔ Creating Own Primary DNS on Linux using bind pakage For Rhel or CentOs ➔ Installing Software packages bind (it helps us create to primary dns) [root@piyush Desktop]# yum install bind -y
- 2. ➔ To see the confriguration file bind [root@piyush Desktop]# rpm -qc bind /etc/logrotate.d/named /etc/named.conf /etc/named.iscdlv.key /etc/named.rfc1912.zones /etc/named.root.key /etc/rndc.conf /etc/rndc.key /etc/sysconfig/named /var/named/named.ca /var/named/named.empty /var/named/named.localhost /var/named/named.loopback ➔ Now takes backup of named.conf file as named.conf.bak ➔ named.conf looks like this ➔ [root@piyush etc]# vim named.conf ➔ Now empty the content of file. [root@piyush etc]# echo > named.conf Now creating the Zone for a particular domain [root@piyush etc]# vim named.conf ● In Image :-
- 3. Note:- Ends every line in named.conf with “;” options :- provides you option where to create zone file and Forwarder DNS directory :- where you want to create your Zone File gives the path here For every create Zone block zone :- for creating zone for different Network having different Ip address Pool "0.168.192.in-addr.arpa" :- Ip address Pool of network “192.168.0.” means write Octet of Network in reverse order. master :- is for Primary DNS 0.168.192.revdns :- Zone file Name (name can be any thing but for convenience use name as Network address ) similarly create Zone for Network “100.100.10.” ➔ Now create the zone file (0.168.192.revdns and 10.100.100.revdns) [root@piyush etc]# cd /var/named/ [root@piyush named]# ls data dynamic named.ca named.empty named.localhost named.loopback slaves ➔ Firstly copy the content of named.localhost in the file 0.168.192.revdns and 10.100.100.revdns (Zone file) [root@piyush named]# cat named.localhost
- 4. [root@piyush named]# cp named.localhost 0.168.192.revdns [root@piyush named]# cp named.localhost 10.100.100.revdns ➔ Make the owner and group of file to named [root@piyush named]#chown named:named 0.168.192.revdns [root@piyush named]#chown named:named 10.100.100.revdns ➔ Now editing the files according to the requirement [root@piyush named]# vim 0.168.192.revdnss ● In image :-
- 5. FQDN:= Fully Qualified Domain Name hostname.domainname.topleveldomain hostname.subdomainname.domainname.topleveldomain Note :- If you writing FQDN them put “.” Dot at end otherwise if you wrinting only hostname no need to put Dot at end. Not necessary to write TTL Entry Format:- RemainingOctetOfIpAddr TTL IN Record_Type FQDN 55 :- remaining Octet of Ip Address means here last octet or host. IN :- Internet abc.piyush.com. :- FQDN RECORD_TYPE PTR :- For Ip address to FQDN conversion CNAME :- Canonical name means here zxc.piyush.com. Points to same Ip addresses 192.168.0.55 and 192.168.0.54 ➔ Similarly for Network 100.100.10 [root@piyush named]# vim 10.100.100.revdnss ● In image :-
- 6. Note:- If firewall is running add dns to firewalld service or flush the firewalld as you wish ➔ Now restart the service if no error in syntax , the service get restart without error [root@piyush Desktop]# systemctl restart named [root@piyush Desktop]# systemctl enable --now named ➔ Now move to another pc or client to check ➔ Firstly adding nameserver as ip of DNS server. root@piyush Desktop]#vim /etc/resolv.conf Now do query :-
- 8. IPv4 of Outer Domain As we haven’t use forwarders in options section of named.conf file your DNS can’t resolve ips whose entry are not mentioned in named.conf file. Note:- Even if your DNS is resolving the FQDN of other ips whose entries are not in named.conf. There are two reasons for it:- 1. It may goes to router through gateway to search the domainname of ip. You can use “ route del -net 0.0.0.0 gw 192.168.0.1 ” to delete gateway on client and DNS server side both. 2. Domainname of that ips may resides in your cache. Now checking ip of facebook and youtube