Setup DNS, NTP and DHCP for a mixed RAC/Internet usage

Note : 

You need to install your RAC Nameserver on a separate Virtualbox image/system as a NON-functional Nameserver can lead to a RAC hang scenario !!

Install BIND / DHCP RPMs and learn the needed configuration commands

Install and verify BIND installation [ bind_libs and bind_utils should be arlready installed ] 
[root@hract21 Desktop]#  yum install bind bind-utils bind-libs
[root@hract21 Desktop]# rpm -qa |grep '^bind'
bind-utils-9.8.2-0.30.rc1.el6_6.1.x86_64
bind-libs-9.8.2-0.30.rc1.el6_6.1.x86_64
bind-9.8.2-0.30.rc1.el6_6.1.x86_64

Install and verify DHCP setup 
Download and install dcping utility;
Download location:  http://pkgs.repoforge.org/dhcping  following package :
    dhcping-1.2-2.2.el6.rf.x86_64.rpm  11-Nov-2010 07:31   16K  RHEL6 and CentOS-6 x86 64bit
[root@ns1 ~]# rpm -i Downloads/dhcping-1.2-2.2.el6.rf.x86_64.rpm
 
[root@hract21 Desktop]# yum install dhcp.x86_64 
Total download size: 1.2 M
Is this ok [y/N]: y
Downloading Packages:
(1/3): dhclient-4.1.1-43.P1.0.1.el6_6.1.x86_64.rpm                                                           | 318 kB     00:00     
(2/3): dhcp-4.1.1-43.P1.0.1.el6_6.1.x86_64.rpm                                                               | 819 kB     00:00     
(3/3): dhcp-common-4.1.1-43.P1.0.1.el6_6.1.x86_64.rpm                                                        | 142 kB     00:00  

[root@hract21 Desktop]#  rpm -qa | grep -i DHCP
dhcp-common-4.1.1-43.P1.0.1.el6_6.1.x86_64
dhcp-4.1.1-43.P1.0.1.el6_6.1.x86_64

Setup Files needed: 
: /etc/named.conf
: /var/named/example.com.db
: /var/named/192.168.2.db
: /var/named/192.168.5.db
: /etc/dhcp/dhcpd.conf
: /etc/sysconfig/dhcpd  
: /etc/dhcp/dhcpd.conf
--> For details how to configure DNS/DHCP please read the details the chapters below. 

Setup,test and configure BIND service 
# service named restart 
# nslookup google.de
Server:        192.168.5.50
Address:    192.168.5.50#53

Non-authoritative answer:
Name:    google.de
Address: 173.194.112.152
Name:    google.de
Address: 173.194.112.159
Name:    google.de
Address: 173.194.112.143
Name:    google.de
Address: 173.194.112.151
#  chkconfig named on chkconfig named --list
named              0:off    1:off    2:on    3:on    4:on    5:on    6:off

Setup,test and configure DHCP service 
# service dhcpd start
Starting dhcpd:                                            [  OK  ]
# chkconfig  dhcpd on
# chkconfig  dhcpd --list
dhcpd              0:off    1:off    2:on    3:on    4:on    5:on    6:off
Verify DHCP setup with  dhcping
[root@hract21 Desktop]#  dhcping -s 192.168.5.50 -c 192.168.5.197 
Got answer from: 192.168.5.50

DNS Server Setup

Our DNS server should have configured the Virtualbox Network Devices 
eth0  -> Bridged Network  : inet addr:192.168.1.XXX  Bcast:192.168.1.255  [ Internet Access ]
eth1  -> Internal Network : inet addr:192.168.5.50   Bcast:192.168.5.255  [ Public RAC Interface ]

eth0      Link encap:Ethernet  HWaddr 08:00:27:E6:71:54  
          inet addr:192.168.1.X  Bcast:192.168.1.255  Mask:255.255.255.0

eth1      Link encap:Ethernet  HWaddr 08:00:27:8D:8A:93  
          inet addr:192.168.5.50  Bcast:192.168.5.255  Mask:255.255.255.0   

Setup files used by  DNS : 
  /etc/named.conf  
  /var/named/example.com.db 
  /var/named/192.168.2.db
  /var/named/192.168.5.db


/etc/named.conf :
options {
    listen-on port 53 {  192.168.5.50; 127.0.0.1; };
    directory     "/var/named";
    dump-file     "/var/named/data/cache_dump.db";
        statistics-file "/var/named/data/named_stats.txt";
        memstatistics-file "/var/named/data/named_mem_stats.txt";
    allow-query     {  any; };
    allow-recursion     {  any; };
    recursion yes;
    dnssec-enable no;
    dnssec-validation no;
};

logging {
        channel default_debug {
                file "data/named.run";
                severity dynamic;
        };
};

zone "." IN {
    type hint;
    file "named.ca";
};
zone    "5.168.192.in-addr.arpa" IN { // Reverse zone
    type master;
    file "192.168.5.db";
        allow-transfer { any; };
    allow-update { none; };
};
zone    "2.168.192.in-addr.arpa" IN { // Reverse zone
    type master;
    file "192.168.2.db";
        allow-transfer { any; };
    allow-update { none; };
};
zone  "example.com" IN {
      type master;
       notify no;
       file "example.com.db";
};

/var/named/example.com.db: 
$TTL 1H         ; Time to live
$ORIGIN example.com.
@       IN      SOA     ns1.example.com.  hostmaster.example.com.  (
                        2009011202      ; serial (todays date + todays serial #)
                        3H              ; refresh 3 hours
                        1H              ; retry 1 hour
                        1W              ; expire 1 week
                        1D )            ; minimum 24 hour
;
             IN     NS        ns1  ; name server for example.com
ns1          IN     A        192.168.5.50
grac41       IN     A        192.168.5.101  
grac42       IN     A        192.168.5.102  
grac43       IN     A        192.168.5.103  
grac41int    IN     A        192.168.2.101  
grac42int    IN     A        192.168.2.102  
grac43int    IN     A        192.168.2.103 
;
$ORIGIN grid4.example.com.
@       IN          NS        gns4.grid4.example.com. ; NS  grid4.example.com
        IN          NS        ns1.example.com.      ; NS example.com
gns4    IN          A         192.168.5.54 ; glue record



/var/named/192.168.5.db :
$TTL 1H
@       IN      SOA     ns1.example.com.  root.domin.com.  (
                        2009011201      ; serial (todays date + todays serial #)
                        3H              ; refresh 3 hours
                        1H              ; retry 1 hour
                        1W              ; expire 1 week
                        1D )            ; minimum 24 hour
      IN    NS    ns1
ns1     IN       A      192.168.5.50
;
50            PTR       ns1.example.com.
54            PTR       gns4.grid4.example.com. ; reverse mapping for GNS
101           PTR       grac41.example.com. 
102           PTR       grac42.example.com. 
103           PTR       grac43.example.com. 
201           PTR       wls1.example.com. 

/var/named/192.168.2.db :
$TTL 1H
@       IN      SOA     ns1.example.com. hostmaster.example.com.  (
                        2009011201      ; serial (todays date + todays serial #)
                        3H              ; refresh 3 hours
                        1H              ; retry 1 hour
                        1W              ; expire 1 week
                        1D )            ; minimum 24 hour
        IN      NS      ns1
ns1     IN       A         192.168.5.50
; 
101          PTR       grac41int.example.com. 
102          PTR       grac42int.example.com. 
103          PTR       grac43int.example.com.


Verify zone files and restart named deamon
[root@ns1 named]#  named-checkconf /etc/named.conf
[root@ns1 named]#  named-checkzone example.com example.com.db
zone example.com/IN: grid.example.com/NS 'gns.grid.example.com' (out of zone) has no addresses records (A or AAAA)
zone example.com/IN: grid12c.example.com/NS 'gns12c.grid12c.example.com' (out of zone) has no addresses records (A or AAAA)
zone example.com/IN: grid2.example.com/NS 'gns2.grid2.example.com' (out of zone) has no addresses records (A or AAAA)
zone example.com/IN: grid3.example.com/NS 'gns3.grid3.example.com' (out of zone) has no addresses records (A or AAAA)
zone example.com/IN: grid4.example.com/NS 'gns4.grid4.example.com' (out of zone) has no addresses records (A or AAAA)
zone example.com/IN: loaded serial 2009011202
OK
[root@ns1 named]# named-checkzone example.com  192.168.5.db
zone example.com/IN: loaded serial 2009011201
OK
[root@ns1 named]# named-checkzone example.com  192.168.2.db
zone example.com/IN: loaded serial 2009011201
OK

Verify DNS Setup

[root@ns1 ~]# nslookup google.de
Server:        192.168.5.50
Address:    192.168.5.50#53

Non-authoritative answer:
Name:    google.de
Address: 173.194.67.94

[root@ns1 ~]# nslookup grac41 
Server:        192.168.5.50
Address:    192.168.5.50#53

Name:    grac41.example.com
Address: 192.168.5.101

[root@ns1 ~]# ping -c 2  google.de
PING google.de (173.194.67.94) 56(84) bytes of data.
64 bytes from wi-in-f94.1e100.net (173.194.67.94): icmp_seq=1 ttl=38 time=66.3 ms
64 bytes from wi-in-f94.1e100.net (173.194.67.94): icmp_seq=2 ttl=38 time=62.3 ms
--- google.de ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1064ms
rtt min/avg/max/mdev = 62.373/64.344/66.316/1.987 ms

[root@ns1 ~]# ping -c 2  grac41 
PING grac41.example.com (192.168.5.101) 56(84) bytes of data.
64 bytes from grac41.example.com (192.168.5.101): icmp_seq=1 ttl=64 time=0.200 ms
 64 bytes from grac41.example.com (192.168.5.101): icmp_seq=2 ttl=64 time=0.293 ms
--- grac41.example.com ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 999ms
rtt min/avg/max/mdev = 0.200/0.246/0.293/0.049 ms

[root@ns1 ~]#  cat /etc/resolv.conf
# Generated by NetworkManager
search example.com grid4.example.com
nameserver 192.168.5.50
[root@ns1 ~]#  netstat -rn
Kernel IP routing table
Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface
0.0.0.0         192.168.1.1     0.0.0.0         UG        0 0          0 eth0
192.168.1.0     0.0.0.0         255.255.255.0   U         0 0          0 eth0
192.168.3.0     0.0.0.0         255.255.255.0   U         0 0          0 eth2
192.168.5.0     0.0.0.0         255.255.255.0   U         0 0          0 eth1

If the GNS server is running the following commands should work too !
[root@ns1 ~]# nslookup grac4-scan
Server:        192.168.5.50
Address:    192.168.5.50#53

Non-authoritative answer:
Name:    grac4-scan.grid4.example.com
Address: 192.168.5.167
Name:    grac4-scan.grid4.example.com
Address: 192.168.5.156
Name:    grac4-scan.grid4.example.com
Address: 192.168.5.153

[root@ns1 ~]# ping -c 2  grac4-scan
PING grac4-scan.grid4.example.com (192.168.5.167) 56(84) bytes of data.
64 bytes from 192.168.5.167: icmp_seq=1 ttl=64 time=0.176 ms
64 bytes from 192.168.5.167: icmp_seq=2 ttl=64 time=0.203 ms
--- grac4-scan.grid4.example.com ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1000ms
rtt min/avg/max/mdev = 0.176/0.189/0.203/0.019 ms
[root@ns1 ~]# dig @192.168.5.50 grac4-scan.grid4.example.com
; <<>> DiG 9.9.3-RedHat-9.9.3-P1.el6 <<>> @192.168.5.50 grac4-scan.grid4.example.com
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 18529
;; flags: qr rd ra; QUERY: 1, ANSWER: 3, AUTHORITY: 2, ADDITIONAL: 2

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;grac4-scan.grid4.example.com.    IN    A

;; ANSWER SECTION:
grac4-scan.grid4.example.com. 94 IN    A    192.168.5.167
grac4-scan.grid4.example.com. 94 IN    A    192.168.5.156
grac4-scan.grid4.example.com. 94 IN    A    192.168.5.153

;; AUTHORITY SECTION:
grid4.example.com.    3600    IN    NS    gns4.grid4.example.com.
grid4.example.com.    3600    IN    NS    ns1.example.com.

;; ADDITIONAL SECTION:
ns1.example.com.    3600    IN    A    192.168.5.50

;; Query time: 1 msec
;; SERVER: 192.168.5.50#53(192.168.5.50)
;; WHEN: Sun Jan 11 17:17:51 CET 2015
;; MSG SIZE  rcvd: 158

[root@ns1 ~]#  dig @192.168.5.54 grac4-scan.grid4.example.com
; <<>> DiG 9.9.3-RedHat-9.9.3-P1.el6 <<>> @192.168.5.54 grac4-scan.grid4.example.com
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 5071
;; flags: qr aa; QUERY: 1, ANSWER: 3, AUTHORITY: 1, ADDITIONAL: 1

;; QUESTION SECTION:
;grac4-scan.grid4.example.com.    IN    A

;; ANSWER SECTION:
grac4-scan.grid4.example.com. 120 IN    A    192.168.5.153
grac4-scan.grid4.example.com. 120 IN    A    192.168.5.156
grac4-scan.grid4.example.com. 120 IN    A    192.168.5.167

;; AUTHORITY SECTION:
grid4.example.com.    10800    IN    SOA    grac4-gns-vip.grid4.example.com. grac4-gns-vip.grid4.example.com. 264601876 10800 10800 30 120

;; ADDITIONAL SECTION:
grac4-gns-vip.grid4.example.com. 10800 IN A    192.168.5.54

;; Query time: 2 msec
;; SERVER: 192.168.5.54#53(192.168.5.54)
;; WHEN: Sun Jan 11 17:17:59 CET 2015
;; MSG SIZE  rcvd: 160

If GNS is not configured or running you will get error:  can't find grac4-scan: NXDOMAIN
[grid@grac41 ~]$  srvctl stop gns
[root@ns1 ~]# ping 192.168.5.54
PING 192.168.5.54 (192.168.5.54) 56(84) bytes of data.
From 192.168.5.50 icmp_seq=2 Destination Host Unreachable
From 192.168.5.50 icmp_seq=3 Destination Host Unreachable
From 192.168.5.50 icmp_seq=4 Destination Host Unreachable
^C
--- 192.168.5.54 ping statistics ---
4 packets transmitted, 0 received, +3 errors, 100% packet loss, time 3944ms
pipe 3
[root@ns1 ~]#  nslookup grac4-scan
Server:        192.168.5.50
Address:    192.168.5.50#53

** server can't find grac4-scan: NXDOMAIN

Verify subdomain delegation with cluvfy

Starting with Oracle Database 11g release 2 (11.2.0.2), use the cluvfy comp dns component verification 
command to verify that the Grid Naming Service (GNS) subdomain delegation has been properly set up in 
the Domain Name Service (DNS) server.

Run cluvfy comp dns -server on one node of the cluster. On each node of the cluster run 
cluvfy comp dns -client to verify the DNS server setup for the cluster.

Oh grac41: 
[root@grac41 ~]# cluvfy comp dns -server -domain  grid4.example.com -vipaddress 192.168.5.54/255.255.255.0/eth1 -verbose
Verifying DNS Check 
Starting the test DNS server on IP "192.168.5.54/255.255.255.0/eth1" listening on port 53
Started the IP address "192.168.5.54/255.255.255.0/eth1" on node "grac41"

On grac42: 
[root@grac42 ~]#  cluvfy comp dns -client -domain  grid4.example.com -vip 192.168.5.54
Verifying DNS Check 
Checking if the IP address "192.168.5.54" is reachable
The IP address "192.168.5.54" is reachable from local node
Successfully connected to test DNS server
Checking if the test DNS server started on address "192.168.5.54", listening on port 53 can be queried
Check output of command "cluvfy comp dns -server" to see if it received IP address lookup for name "grac42.grid4.example.com"
Successfully connected to the test DNS server started on address "192.168.5.54", listening on port 53
Checking DNS delegation for the GNS subdomain "grid4.example.com"...
Check output of command "cluvfy comp dns -server" to see if it received IP address lookup for name "grac42.grid4.example.com"
Successfully verified DNS delegation of the GNS subdomain "grid4.example.com"

Verification of DNS Check was successful. 

--> Server should report 
Received IP address lookup query for name "grac42.grid4.example.com"
Received IP address lookup query for name "grac42.grid4.example.com"

On grac43:
[root@grac43 ~]# cluvfy comp dns -client -domain  grid4.example.com -vip 192.168.5.54
..
Verification of DNS Check was successful. 
--> Server should report 
Received IP address lookup query for name "grac43.grid4.example.com"
Received IP address lookup query for name "grac43.grid4.example.com"

On grac41 
[root@grac41 Desktop]#  cluvfy comp dns -client -domain  grid4.example.com -vip 192.168.5.54 
..
Verification of DNS Check was successful. 
--> Server should report 
Received IP address lookup query for name "grac41.grid4.example.com"
Received IP address lookup query for name "grac41.grid4.example.com"

 

Setup DHCP server

DHCP configuration file 
/etc/dhcp/dhcpd.conf :
ddns-update-style interim;
ignore client-updates;

subnet 192.168.5.0 netmask 255.255.255.0 {
        option routers                  192.168.5.1;                    # Default gateway to be used by DHCP clients
        option subnet-mask              255.255.255.0;                  # Default subnet mask to be used by DHCP clients.
        option ip-forwarding            off;                            # Do not forward DHCP requests.
        option broadcast-address        192.168.5.255;                  # Default broadcast address to be used by DHCP client.
        option domain-name-servers      192.168.5.50;                   # IP address of the DNS server. 
        option time-offset              -19000;                           # Central Standard Time
        option ntp-servers              192.168.5.50;                   # Default NTP server to be used by DHCP clients
        range                           192.168.5.150 192.168.5.254;    # Range of IP addresses that can be issued to DHCP client
        default-lease-time              21600;                            # Amount of time in seconds that a client may keep the IP address
        max-lease-time                  43200;
} 

/etc/sysconfig/dhcpd
# Command line options here
DHCPDARGS="eth1"

Restart the DHCP server :
[root@ns1 network-scripts]# service dhcpd restart

 

Verify  DHCP setup with cluvfy

[root@grac41 ~]#  $GRID_HOME/bin/cluvfy comp dhcp -clustername grac4 
Verifying DHCP Check 
Checking if any DHCP server exists on the network...
PRVG-5723 : Network CRS resource is configured to use DHCP provided IP addresses

Verification of DHCP Check was unsuccessful on all the specified nodes. 

From Oracle docu :
- You must run this command as root.
- Do not run this check while the default network Oracle Clusterware resource, configured to use a 
   DHCP-provided IP address, is online (because the VIPs get released and, since the cluster is online, 
   DHCP has provided IP, so there is no need to double the load on the DHCP server).
- Before running this command, ensure that the network resource is offline. Use the srvctl stop nodeapps command 
   to bring the network resource offline, if necessary.

As we are on a test cluster go ahead and stop the Nodeapps 
[root@grac41 Desktop]#  srvctl stop nodeapps -f

[root@grac41 ~]# $GRID_HOME/bin/cluvfy comp dhcp -clustername grac4 -verbose
Verifying DHCP Check 
Checking if any DHCP server exists on the network...
Checking if network CRS resource is configured and online
Network CRS resource is offline or not configured. Proceeding with DHCP checks.
CRS-10009: DHCP server returned server: 192.168.5.50, loan address : 192.168.5.165/255.255.255.0, lease time: 21600

At least one DHCP server exists on the network and is listening on port 67
Checking if DHCP server has sufficient free IP addresses for all VIPs...
Sending DHCP "DISCOVER" packets for client ID "grac4-scan1-vip"
CRS-10009: DHCP server returned server: 192.168.5.50, loan address : 192.168.5.165/255.255.255.0, lease time: 21600
...
CRS-10012: released DHCP server lease for client ID grac4-scan3-vip on port 67
CRS-10012: released DHCP server lease for client ID grac4-grac41-vip on port 67

DHCP server was able to provide sufficient number of IP addresses
The DHCP server response time is within acceptable limits
Verification of DHCP Check was successful. 

Note you can track  the lease operation with following OS command 
[root@ns1 ~]# tail -f  /var/lib/dhcpd/dhcpd.leases
}
lease 192.168.5.164 {
  starts 0 2015/01/11 17:29:10;
  ends 0 2015/01/11 17:29:10;
  tstp 0 2015/01/11 17:29:10;
  cltt 0 2015/01/11 17:29:10;
  binding state free;
  hardware ethernet 00:00:00:00:00:00;
  uid "\000grac4-grac41-vip";
}

 

Configure NTP


Configuration script :
/etc/ntp.conf
restrict default nomodify notrap noquery
restrict 127.0.0.1 
# -- CLIENT NETWORK -------
restrict 192.168.5.0 mask 255.255.255.0 nomodify notrap
# --- OUR TIMESERVERS -----  can't reach NTP servers - build my own server 
server 0.pool.ntp.org iburst
server 1.pool.ntp.org iburst
server 127.127.1.0
# --- NTP MULTICASTCLIENT ---
# --- GENERAL CONFIGURATION ---
# Undisciplined Local Clock.
fudge   127.127.1.0 stratum 9
# Drift file.
driftfile /var/lib/ntp/drift
broadcastdelay  0.008
# Keys file.
keys /etc/ntp/keys

Restart NTP daemon
[root@ns1 network-scripts]# service ntpd restart
Shutting down ntpd:                                        [  OK  ]
Starting ntpd:                                             [  OK  ]

Verify setup
[root@ns1 network-scripts]# ntpq -p
     remote           refid      st t when poll reach   delay   offset  jitter
==============================================================================
 foxtrot.zq1.de  122.227.206.195  3 u    2   64    1   68.504  4608.38   1.115
 der.beste.tiger 159.173.11.127   3 u    1   64    1   38.195  4603.43  11.063
 LOCAL(0)        .LOCL.           9 l    2   64    1    0.000    0.000   0.000

 

Verify NTP setup with cluvfy

Verify NTP setup with cluvfy 
[grid@grac41 ~]$   cluvfy comp clocksync
Verifying Clock Synchronization across the cluster nodes 
Checking if Clusterware is installed on all nodes...
Check of Clusterware install passed
Checking if CTSS Resource is running on all nodes...
CTSS resource check passed
Querying CTSS for time offset on all nodes...
Query of CTSS for time offset passed
Check CTSS state started...
CTSS is in Observer state. Switching over to clock synchronization checks using NTP
Starting Clock synchronization checks using Network Time Protocol(NTP)...
NTP Configuration file check started...
NTP Configuration file check passed
Checking daemon liveness...
Liveness check passed for "ntpd"
Check for NTP daemon or service alive passed on all nodes
NTP daemon slewing option check passed
NTP daemon's boot time configuration check for slewing option passed
NTP common Time Server Check started...
Check of common NTP Time Server passed
Clock time offset check from NTP Time Server started...
Clock time offset check passed
Clock synchronization check using Network Time Protocol(NTP) passed
Oracle Cluster Time Synchronization Services check passed
Verification of Clock Synchronization across the cluster nodes was successful.

Reference

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