Ch 19 DNS (BIND)
IP to host and host to IP resolve..
.com – commercial
.org – organization
.mel – meltem
.co.in – India (only)
.gov - government
.travel – Travel Domain
Packages required for BIND
#rpm –qa |grep bind
bind 2nd C.D
bind-chroot 2nd C.D
bind-devels 3rd C.D
bind-utils 3rd C.D
Caching-name server 4th C.D
System-config-bind
# cd /var/named/chroot/etc
# Create named.conf (using 2 files)
# vi named.conf
# vi named.caching.servername.conf
till allow.query ( 11 Lines copy to named.conf)
# vi named.rfc.1912.zones
from Zone “.” IN
to Zone 0.0.0.0.0.0
Copy that lines & append in named.conf.
We can use cat >> command to do above copy and paste job..
# cd /var/named/chroot/var/named.
Local.zone ----> forward
Named.local ----> Reserve
# cp Localhost.zone domain.fzone
# cp named.local domain.rzone
DNS Theory
In networking including the internet user locate other computers by name. This frees users from the task of remember numeric
Address of net resources.
The most effective way to configure the network to allow such name base connection is to setup Domain name service or a name server
Which resolve hostname on the network in to numerical address and vise versa.
DNS associate host name with their respective IP address so that when user want to connect to other machine on the network they can refer to them by name without having to remember IP address.
DNS is normally implement using centralize servers that are authoritative for some Domains and refer to other DNS server to other domains.
When a client host request information from a Name server it usually connect to port 53 the name server then attempts to resolve the FQDN ( fully qualified domain name) best on its resolve library which may contain authoritative information about the host. Requested or cache data from an earlier query IF the Name server doesn’t already have the answer in its resolve library its query other name server to determine which name server are authority for the FQDN with information its query autho. Name server to determine the IP address of the requested host.
IF reveres Lookup Zone perform the same process is used. A scope that query is made with an unknown IP address return then name.
NAME SERVER ZONE.
The FQDN of host can be bracken into different segment this segment
Are Organized into hierarchy (like tree) with a main trunk , primary
Branches and e.g. stn3.swappy.neil.com
When looking FQDN resolve to find the IP addresses to reflect particular system read the name right to left which is level of hierarchy divided by period (.) in this example first top level domain for this FQDN.
The name neil is some domain under com while swappy sub domain under neil the name stn3 identifying a specific machine hostname.
Where are zone file, zone file stored in primary name server also called master name server with are truly authority and where change
are to file and secondary name server also called slave name server which received their zone file from primary name server.
Zone
Forward lookup zone
Reverse lookup zone
slave server
*) master name server type master store organize and authoritative zone record for name space and answer query about the name space from other name server.
*) slave server
answer query from their name server concerning name species for which it is consider as authority however slave name server get their name space.
Package require
bind
caching-name server
files :
# /var/named/chroot/etc/name.conf
# /var/named/chroot/var/named/
# vi localhost.zone
# vi named.local
# vi /etc/resolve.conf
# vi /etc/hosts
# rpm –qa |grep bind
# yum install bind*
#rpm –qa |grep caching
#yum install caching*
#cd /var/named/chroot/etc
#vi named.rfc1912.zones
# cp named.rfc1912.zones named.conf
# vi named.conf
# vi named.caching-nameserver.conf
Copy options{
};
paste in (named.conf) named.conf at starting of file.
Options {
Listen –on port 53{127.0.0.1};
#vi named.conf
copy zone line 11 line and paste below zone file above IPv6 line.
Zone “
};
Zone “lion.com.” In {
Type master;
file”line.fzone”;
allow-update{none;};
};
Zone “9.147.167.in-addr.arpa”In{
(reveres ip decided on class I.E a b c)
type master;
file “lion.rzone”;
allow-update {none;};
};
option{
listen on port 53 {167.147.9.3}
allow-query {167.147.9.3;};
#chown named named.conf
#cd /var/named/chroot/var/named
# cp localhost.zone line.fzone
# cp named.local line.rzone
#chown named lion.fzone
#chown named lion.rzone
#vi lion.fzone
# IN ------> internet name
# SOA -----> start of authority
# A -------> Address
# NS ------> Name server
# PTR -----> Pointer record
# $TTL ----> Time to leave
$TTL 86400
In SOA stn3.lion.com.root.lion.com. (
IN NS stn3.lion.com.
IN A 167.147.9.3
IN AAAA ::1
Stn3 IN A 167.147.9.3
www IN A 167.147.9.3
)
# vi lion.rzone
$TTL 86400
@ In SOA stn3.lion.com.root.lion.com. (
# “3” why three? System ip 167.147.1.3 for Class B use last octet)
IN NS stn3.lion.com.
3 IN PTR stn3.lion.com.
3 IN PTR www.
)
#vi /etc/resove.conf
search lion.com
nameserver 167.147.9.3
#vi /etc/hosts
167.147.9.3 stn3.lion.com stn3
# service named restart
# nslookup stn3.lion.com
# nslookup 167.147.9.3
# nslookup www.lion.com
DIG ( domain information groper)
# dig stn3.lion.com
# dig –x 167.147.9.3
Slave Server
Same step to install slave server as master server.
# vi named.conf
Zone “lion.com.” In {
Type slave;
Masters{167.147.9.3;};
File “slaves/lion.fzone”;
};
Zone “9.147.167.in-addr.arpa” IN {
(reveres ip decided on class I.E a b c)
type slave;
file “lion.rzone”;
Masters{167.147.9.3;};
File “slaves/lion.rzone”;
};
# chown named named.conf
#vi /etc/resove.conf
search lion.com
nameserver 167.147.9.3
# service named restart
# cd /var/named/chroot/var/named
#cd slaves
Both file added automatically from master server after service restart.