Hack The Sec-Leading Resource Of Linux Tutorial: Caching-Only

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<span style="color: #990000; font-size: x-large;">Install and Configure Caching-Only DNS Server in RHEL/CentOS 7</span><br />
<span style="background-color: white; font-family: Verdana, sans-serif; line-height: 28.8px;">DNS servers comes in several types such as master, slave, forwarding and cache, to name a few examples, with cache-only DNS being the one that is easier to setup. Since DNS uses the UDP protocol, it improves the query time because it does not require an acknowledgement.</span><br />
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjGmlA863bI-9bY9VrlFYVC-uB7nhDSRVe3oqRhIjT0ACX5k3aih65GwI1OegSFwsV_S82UZ8u84NNlNHPkgkfW_BTIbJ9xxAA2PCPELHRQNoIJwPBiCM7Jjj0SlsOzskdVbHOUOXHReufH/s1600/Setup-Cache-Only-DNS-in-CentOS-RHEL-7_www.hackthesec.co.in.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="306" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjGmlA863bI-9bY9VrlFYVC-uB7nhDSRVe3oqRhIjT0ACX5k3aih65GwI1OegSFwsV_S82UZ8u84NNlNHPkgkfW_BTIbJ9xxAA2PCPELHRQNoIJwPBiCM7Jjj0SlsOzskdVbHOUOXHReufH/s640/Setup-Cache-Only-DNS-in-CentOS-RHEL-7_www.hackthesec.co.in.png" width="640" /></a></div>
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<li><span style="background-color: white; font-family: 'roboto condensed', arial, sans-serif; font-size: 18px; line-height: 28.8px;"><a href="http://www.hackthesec.co.in/2016/01/how-to-setup-dns-bind-server-on.html" target="_blank"><span style="color: red;">How to Setup DNS (Bind) Server on CentOS/RHEL 7/6/5</span></a></span></li>
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<span style="background-color: white; font-family: Verdana, sans-serif; line-height: 28.8px;">The cache-only DNS server is also known as resolver, which will query DNS records and fetch all the DNS details from other servers, and keep each query request in its cache for later use so that when we perform the same request in the future, it will serve from its cache, thus reducing the response time even more.</span><br />
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<span style="color: #0b5394; font-family: Arial, Helvetica, sans-serif; font-size: small;"><span style="font-family: Arial, Helvetica, sans-serif; font-size: large; line-height: 18px;"><u>My Testing Environment</u></span></span></div>
<pre style="background: none 0px 0px repeat scroll rgb(60, 60, 60); border-radius: 4px; border: 1px solid rgb(229, 229, 229); margin-bottom: 20px; outline: 0px; overflow: auto; padding: 20px; vertical-align: baseline;"><span style="color: white;"><span style="font-size: 12px; line-height: 15.6000003814697px;">DNS server  : dns.hackthesec.co.in (Red Hat Enterprise Linux 7.1)
Server IP Address : 192.168.1.17
Client   : node1.</span></span><span style="color: white; font-size: 12px; line-height: 15.6000003814697px;">hackthesec.co.in</span><span style="color: white; font-size: 12px; line-height: 15.6000003814697px;"> (CentOS 7.1)</span>
<span style="color: white;"><span style="font-size: 12px; line-height: 15.6000003814697px;">Client IP Address : 192.168.1.35</span></span></pre>
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<span style="color: #0b5394; font-family: "arial" , "helvetica" , sans-serif;"><span style="line-height: 18px;">Step 1: Installing Cache-Only DNS Server in RHEL/CentOS 7</span></span></div>
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<span style="line-height: 28.7999992370605px;"><span style="font-family: "arial" , "helvetica" , sans-serif;">1.The Cache-Only DNS server, can be installed via the bind package. If you don’t remember the package name, you can do a quick search for the package name using the command below.</span></span></div>
<pre style="background: none 0px 0px repeat scroll rgb(60, 60, 60); border-radius: 4px; border: 1px solid rgb(229, 229, 229); margin-bottom: 20px; outline: 0px; overflow: auto; padding: 20px; vertical-align: baseline;"><span style="color: white;"><span style="font-size: 12px; line-height: 15.6000003814697px;"># yum search bind</span></span></pre>
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<span style="font-family: "arial" , "helvetica" , sans-serif;"><span style="border-image-outset: initial; border-image-repeat: initial; border-image-slice: initial; border-image-source: initial; border-image-width: initial; border: 0px; font-stretch: inherit; line-height: 28.7999992370605px; margin: 0px; padding: 0px; vertical-align: baseline;">2.</span><span style="line-height: 28.7999992370605px;"> In the above result, you will see several packages. From those, we need to choose and install only</span><span style="border-image-outset: initial; border-image-repeat: initial; border-image-slice: initial; border-image-source: initial; border-image-width: initial; border: 0px; font-stretch: inherit; line-height: 28.7999992370605px; margin: 0px; padding: 0px; vertical-align: baseline;">bind</span><span style="line-height: 28.7999992370605px;"> and </span><span style="border-image-outset: initial; border-image-repeat: initial; border-image-slice: initial; border-image-source: initial; border-image-width: initial; border: 0px; font-stretch: inherit; line-height: 28.7999992370605px; margin: 0px; padding: 0px; vertical-align: baseline;">bind-utils</span><span style="line-height: 28.7999992370605px;"> packages using following yum command.</span></span></div>
<pre style="background: none 0px 0px repeat scroll rgb(60, 60, 60); border-radius: 4px; border: 1px solid rgb(229, 229, 229); margin-bottom: 20px; outline: 0px; overflow: auto; padding: 20px; vertical-align: baseline;"><span style="color: white;"><span style="font-size: 12px; line-height: 15.6000003814697px;"># yum install bind bind-utils -y</span></span></pre>
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<span style="color: #0b5394; font-family: "arial" , "helvetica" , sans-serif; font-size: medium;"><span style="line-height: 18px;">Step 2: Configure Cache-Only DNS in RHEL/CentOS 7</span></span></div>
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<span style="font-family: "arial" , "helvetica" , sans-serif;"><span style="border: 0px; font-stretch: inherit; line-height: 28.7999992370605px; margin: 0px; padding: 0px; vertical-align: baseline;">3.</span><span style="line-height: 28.7999992370605px;"> Once DNS packages are installed we can go ahead and configure DNS. Open and edit</span></span></div>
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<span style="font-family: "arial" , "helvetica" , sans-serif;"><code style="background: none 0px 0px repeat scroll rgb(246, 246, 248); border-radius: 3px; border: 1px solid rgb(158, 158, 159); font-stretch: inherit; font-weight: 600; line-height: 1.6; margin: 0px; max-width: 100%; overflow: auto; padding: 2px; vertical-align: baseline; white-space: pre;">/etc/named.conf</code><span style="line-height: 28.7999992370605px;"> using your preferred text editor. Make the changes suggested below (or you can use your settings as per your requirements).</span></span></div>
<pre style="background: none 0px 0px repeat scroll rgb(60, 60, 60); border-radius: 4px; border: 1px solid rgb(229, 229, 229); margin-bottom: 20px; outline: 0px; overflow: auto; padding: 20px; vertical-align: baseline;"><span style="color: white;"><span style="font-size: 12px; line-height: 15.6000003814697px;">listen-on port 53 { 127.0.0.1; any; };
allow-query     { localhost; any; };
allow-query-cache       { localhost; any; };</span></span></pre>
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<span style="font-family: "arial" , "helvetica" , sans-serif;">These directives instruct the DNS server to listen on <span style="border-image-outset: initial; border-image-repeat: initial; border-image-slice: initial; border-image-source: initial; border-image-width: initial; border: 0px; font-stretch: inherit; font-style: inherit; font-variant: inherit; line-height: inherit; margin: 0px; padding: 0px; vertical-align: baseline;">UDP</span> port <span style="border-image-outset: initial; border-image-repeat: initial; border-image-slice: initial; border-image-source: initial; border-image-width: initial; border: 0px; font-stretch: inherit; font-style: inherit; font-variant: inherit; line-height: inherit; margin: 0px; padding: 0px; vertical-align: baseline;">53</span>, and to allow queries and caches responses from <span style="border-image-outset: initial; border-image-repeat: initial; border-image-slice: initial; border-image-source: initial; border-image-width: initial; border: 0px; font-stretch: inherit; font-style: inherit; font-variant: inherit; line-height: inherit; margin: 0px; padding: 0px; vertical-align: baseline;">localhost</span> and any other machine that reaches the server.</span></div>
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<span style="font-family: "arial" , "helvetica" , sans-serif;"><span style="border-image-outset: initial; border-image-repeat: initial; border-image-slice: initial; border-image-source: initial; border-image-width: initial; border: 0px; font-stretch: inherit; font-style: inherit; font-variant: inherit; line-height: inherit; margin: 0px; padding: 0px; vertical-align: baseline;">4.</span> It is important to note that the ownership of this file must be set to <code style="background-attachment: scroll; background-clip: initial; background-color: #f6f6f8; background-image: none; background-origin: initial; background-position: 0px 0px; background-repeat: repeat; background-size: initial; border-image-outset: initial; border-image-repeat: initial; border-image-slice: initial; border-image-source: initial; border-image-width: initial; border-radius: 3px; border: 1px solid rgb(158, 158, 159); font-stretch: inherit; font-style: inherit; font-variant: inherit; font-weight: 600; line-height: 1.6; margin: 0px; max-width: 100%; overflow: auto; padding: 2px; vertical-align: baseline; white-space: pre;">root:named</code> and also if<span style="border-image-outset: initial; border-image-repeat: initial; border-image-slice: initial; border-image-source: initial; border-image-width: initial; border: 0px; font-stretch: inherit; font-style: inherit; font-variant: inherit; line-height: inherit; margin: 0px; padding: 0px; vertical-align: baseline;">SELinux</span> is enabled, after editing the configuration file we need to make sure that its context is set to<code style="background-attachment: scroll; background-clip: initial; background-color: #f6f6f8; background-image: none; background-origin: initial; background-position: 0px 0px; background-repeat: repeat; background-size: initial; border-image-outset: initial; border-image-repeat: initial; border-image-slice: initial; border-image-source: initial; border-image-width: initial; border-radius: 3px; border: 1px solid rgb(158, 158, 159); font-stretch: inherit; font-style: inherit; font-variant: inherit; font-weight: 600; line-height: 1.6; margin: 0px; max-width: 100%; overflow: auto; padding: 2px; vertical-align: baseline; white-space: pre;">named_conf_t</code> as shown in Fig. 4 (same thing for the auxiliary file <code style="background-attachment: scroll; background-clip: initial; background-color: #f6f6f8; background-image: none; background-origin: initial; background-position: 0px 0px; background-repeat: repeat; background-size: initial; border-image-outset: initial; border-image-repeat: initial; border-image-slice: initial; border-image-source: initial; border-image-width: initial; border-radius: 3px; border: 1px solid rgb(158, 158, 159); font-stretch: inherit; font-style: inherit; font-variant: inherit; font-weight: 600; line-height: 1.6; margin: 0px; max-width: 100%; overflow: auto; padding: 2px; vertical-align: baseline; white-space: pre;">/etc/named.rfc1912.zones</code>):</span></div>
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<pre style="background: none 0px 0px repeat scroll rgb(60, 60, 60); border-radius: 4px; border: 1px solid rgb(229, 229, 229); margin-bottom: 20px; outline: 0px; overflow: auto; padding: 20px; vertical-align: baseline;"><span style="color: white;"><span style="font-size: 12px; line-height: 15.6000003814697px;"># ls -lZ /etc/named.conf
# ls -lZ /etc/named.rfc1912.zones</span></span></pre>
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<span style="line-height: 28.7999992370605px;"><span style="font-family: "arial" , "helvetica" , sans-serif;">Otherwise, configure the SELinux context before proceeding:</span></span></div>
<pre style="background: none 0px 0px repeat scroll rgb(60, 60, 60); border-radius: 4px; border: 1px solid rgb(229, 229, 229); margin-bottom: 20px; outline: 0px; overflow: auto; padding: 20px; vertical-align: baseline;"><span style="color: white;"><span style="font-size: 12px; line-height: 15.6000003814697px;"># semanage fcontext -a -t named_conf_t /etc/named.conf
# semanage fcontext -a -t named_conf_t /etc/named.rfc1912.zones</span></span></pre>
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<span style="font-family: "arial" , "helvetica" , sans-serif;"><span style="border-image-outset: initial; border-image-repeat: initial; border-image-slice: initial; border-image-source: initial; border-image-width: initial; border: 0px; font-stretch: inherit; line-height: 28.7999992370605px; margin: 0px; padding: 0px; vertical-align: baseline;">5.</span><span style="line-height: 28.7999992370605px;"> Additionally, we need to test the DNS configuration now for some syntax error before starting the bind service:</span></span></div>
<pre style="background: none 0px 0px repeat scroll rgb(60, 60, 60); border-radius: 4px; border: 1px solid rgb(229, 229, 229); margin-bottom: 20px; outline: 0px; overflow: auto; padding: 20px; vertical-align: baseline;"><span style="color: white;"><span style="font-size: 12px; line-height: 15.6000003814697px;"># named-checkconf /etc/named.conf</span></span></pre>
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<span style="font-family: "arial" , "helvetica" , sans-serif;"><span style="border-image-outset: initial; border-image-repeat: initial; border-image-slice: initial; border-image-source: initial; border-image-width: initial; border: 0px; font-stretch: inherit; line-height: 28.7999992370605px; margin: 0px; padding: 0px; vertical-align: baseline;">6.</span><span style="line-height: 28.7999992370605px;"> After the syntax verification results seems perfect, restart the </span><span style="border-image-outset: initial; border-image-repeat: initial; border-image-slice: initial; border-image-source: initial; border-image-width: initial; border: 0px; font-stretch: inherit; line-height: 28.7999992370605px; margin: 0px; padding: 0px; vertical-align: baseline;">named</span><span style="line-height: 28.7999992370605px;"> service to take new changes into effect and also make the service to auto start across system boots, and then check its status:</span></span></div>
<pre style="background: none 0px 0px repeat scroll rgb(60, 60, 60); border-radius: 4px; border: 1px solid rgb(229, 229, 229); margin-bottom: 20px; outline: 0px; overflow: auto; padding: 20px; vertical-align: baseline;"><span style="color: white;"><span style="font-size: 12px; line-height: 15.6000003814697px;"># systemctl restart named
# systemctl enable named
# systemctl status named</span></span></pre>
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<span style="font-family: "arial" , "helvetica" , sans-serif;"><span style="border-image-outset: initial; border-image-repeat: initial; border-image-slice: initial; border-image-source: initial; border-image-width: initial; border: 0px; font-stretch: inherit; line-height: 28.7999992370605px; margin: 0px; padding: 0px; vertical-align: baseline;">7.</span><span style="line-height: 28.7999992370605px;"> Next, open the port 53 on the firewall.</span></span></div>
<pre style="background: none 0px 0px repeat scroll rgb(60, 60, 60); border-radius: 4px; border: 1px solid rgb(229, 229, 229); margin-bottom: 20px; outline: 0px; overflow: auto; padding: 20px; vertical-align: baseline;"><span style="color: white;"><span style="font-size: 12px; line-height: 15.6000003814697px;"># firewall-cmd --add-port=53/udp
# firewall-cmd --add-port=53/udp --permanent</span></span></pre>
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<span style="color: #0b5394; font-family: "arial" , "helvetica" , sans-serif; font-size: medium;"><span style="line-height: 18px;">Step 3: Chroot Cache-Only DNS Server in RHEL and CentOS 7</span></span></div>
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<span style="font-family: "arial" , "helvetica" , sans-serif;"><span style="border: 0px; font-stretch: inherit; line-height: 28.7999992370605px; margin: 0px; padding: 0px; vertical-align: baseline;">8.</span><span style="line-height: 28.7999992370605px;"> If you wish to deploy the Cache-only DNS server within </span><span style="border: 0px; font-stretch: inherit; line-height: 28.7999992370605px; margin: 0px; padding: 0px; vertical-align: baseline;">chroot</span><span style="line-height: 28.7999992370605px;"> environment, you need to have the package </span><span style="border: 0px; font-stretch: inherit; line-height: 28.7999992370605px; margin: 0px; padding: 0px; vertical-align: baseline;">chroot</span><span style="line-height: 28.7999992370605px;"> installed on the system and no further configuration is needed as it by default hard-link to chroot.</span></span></div>
<pre style="background: none 0px 0px repeat scroll rgb(60, 60, 60); border-radius: 4px; border: 1px solid rgb(229, 229, 229); margin-bottom: 20px; outline: 0px; overflow: auto; padding: 20px; vertical-align: baseline;"><span style="color: white;"><span style="font-size: 12px; line-height: 15.6000003814697px;"># yum install bind-chroot -y</span></span></pre>
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<span style="font-family: "arial" , "helvetica" , sans-serif;"><span style="line-height: 28.7999992370605px;">Once </span><span style="border-image-outset: initial; border-image-repeat: initial; border-image-slice: initial; border-image-source: initial; border-image-width: initial; border: 0px; font-stretch: inherit; line-height: 28.7999992370605px; margin: 0px; padding: 0px; vertical-align: baseline;">chroot</span><span style="line-height: 28.7999992370605px;"> package has been installed, you can restart named to take the new changes into effect:</span></span></div>
<pre style="background: none 0px 0px repeat scroll rgb(60, 60, 60); border-radius: 4px; border: 1px solid rgb(229, 229, 229); margin-bottom: 20px; outline: 0px; overflow: auto; padding: 20px; vertical-align: baseline;"><span style="color: white;"><span style="font-size: 12px; line-height: 15.6000003814697px;"># systemctl restart named</span></span></pre>
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<span style="font-family: "arial" , "helvetica" , sans-serif;"><span style="border-image-outset: initial; border-image-repeat: initial; border-image-slice: initial; border-image-source: initial; border-image-width: initial; border: 0px; font-stretch: inherit; line-height: 28.7999992370605px; margin: 0px; padding: 0px; vertical-align: baseline;">9.</span><span style="line-height: 28.7999992370605px;"> Next, create a symbolic link (also named </span><code style="background-attachment: scroll; background-clip: initial; background-color: #f6f6f8; background-image: none; background-origin: initial; background-position: 0px 0px; background-repeat: repeat; background-size: initial; border-image-outset: initial; border-image-repeat: initial; border-image-slice: initial; border-image-source: initial; border-image-width: initial; border-radius: 3px; border: 1px solid rgb(158, 158, 159); font-stretch: inherit; font-weight: 600; line-height: 1.6; margin: 0px; max-width: 100%; overflow: auto; padding: 2px; vertical-align: baseline; white-space: pre;">/etc/named.conf</code><span style="line-height: 28.7999992370605px;">) inside </span><code style="background-attachment: scroll; background-clip: initial; background-color: #f6f6f8; background-image: none; background-origin: initial; background-position: 0px 0px; background-repeat: repeat; background-size: initial; border-image-outset: initial; border-image-repeat: initial; border-image-slice: initial; border-image-source: initial; border-image-width: initial; border-radius: 3px; border: 1px solid rgb(158, 158, 159); font-stretch: inherit; font-weight: 600; line-height: 1.6; margin: 0px; max-width: 100%; overflow: auto; padding: 2px; vertical-align: baseline; white-space: pre;">/var/named/chroot/etc/</code><span style="line-height: 28.7999992370605px;">:</span></span></div>
<pre style="background: none 0px 0px repeat scroll rgb(60, 60, 60); border-radius: 4px; border: 1px solid rgb(229, 229, 229); margin-bottom: 20px; outline: 0px; overflow: auto; padding: 20px; vertical-align: baseline;"><span style="color: white;"><span style="font-size: 12px; line-height: 15.6000003814697px;"># ln -s /etc/named.conf /var/named/chroot/etc/named.conf</span></span></pre>
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<span style="color: #0b5394; font-family: "arial" , "helvetica" , sans-serif; font-size: medium;"><span style="line-height: 18px;">Step 4: Configure DNS on Client Machine</span></span></div>
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<span style="font-family: "arial" , "helvetica" , sans-serif;"><span style="border: 0px; font-stretch: inherit; line-height: 28.7999992370605px; margin: 0px; padding: 0px; vertical-align: baseline;">10.</span><span style="line-height: 28.7999992370605px;"> Add the DNS Cache servers </span><span style="border: 0px; font-stretch: inherit; line-height: 28.7999992370605px; margin: 0px; padding: 0px; vertical-align: baseline;">IP 192.168.0.18</span><span style="line-height: 28.7999992370605px;"> as resolver to the client machine. Edit</span><code style="background: none 0px 0px repeat scroll rgb(246, 246, 248); border-radius: 3px; border: 1px solid rgb(158, 158, 159); font-stretch: inherit; font-weight: 600; line-height: 1.6; margin: 0px; max-width: 100%; overflow: auto; padding: 2px; vertical-align: baseline; white-space: pre;">/etc/sysconfig/network-scripts/ifcfg-eth0</code><span style="line-height: 28.7999992370605px;"> as shown in the following figure:</span></span></div>
<pre style="background: none 0px 0px repeat scroll rgb(60, 60, 60); border-radius: 4px; border: 1px solid rgb(229, 229, 229); margin-bottom: 20px; outline: 0px; overflow: auto; padding: 20px; vertical-align: baseline;"><span style="color: white;"><span style="font-size: 12px; line-height: 15.6000003814697px;">DNS=192.168.1.17</span></span></pre>
<pre style="background: none 0px 0px repeat scroll rgb(60, 60, 60); border-radius: 4px; border: 1px solid rgb(229, 229, 229); margin-bottom: 20px; outline: 0px; overflow: auto; padding: 20px; vertical-align: baseline;"><span style="color: white;"><span style="font-size: 12px; line-height: 15.6000003814697px;">HWADDR=00:1A:4D:9A:F7:CE
TYPE=Ethernet
BOOTPROTO=static
IPADDR=192.168.1.35
NETMASK=255.255.255.0
GATEWAY=192.168.1.1
NM_CONTROLLED=no
DEFROUTE=yes
PEERDNS=yes
IPV4_FAILURE_FATAL=no
IPV6INIT=yes
IPV6_AUTOCONF=yes
IPV6_DEFFROUTE=yes
IPV6_PEERDNS=yes
IPV6_PEEROUTER=yes
IPV6_FAILURE_FATAL=no
NAME=eth0
DNS=192.168.1.17
ONBOOT=yes</span></span></pre>
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<span style="color: #272727; font-family: "roboto condensed" , "arial" , sans-serif; line-height: 28.7999992370605px;">And </span><span style="border: 0px; font-family: "roboto condensed" , "arial" , sans-serif; font-stretch: inherit; line-height: 28.7999992370605px; margin: 0px; padding: 0px; vertical-align: baseline;">/etc/resolv.conf</span><span style="color: #272727; font-family: "roboto condensed" , "arial" , sans-serif; line-height: 28.7999992370605px;"> as follows:</span></div>
<pre style="background: none 0px 0px repeat scroll rgb(60, 60, 60); border-radius: 4px; border: 1px solid rgb(229, 229, 229); margin-bottom: 20px; outline: 0px; overflow: auto; padding: 20px; vertical-align: baseline;"><span style="color: white;"><span style="font-size: 12px; line-height: 15.6000003814697px;">nameserver 192.168.1.17</span></span></pre>
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<span style="font-family: "arial" , "helvetica" , sans-serif;"><span style="border-image-outset: initial; border-image-repeat: initial; border-image-slice: initial; border-image-source: initial; border-image-width: initial; border: 0px; font-stretch: inherit; font-style: inherit; font-variant: inherit; line-height: inherit; margin: 0px; padding: 0px; vertical-align: baseline;">11.</span> Finally it’s time to check our cache server. To do this, you can use dig utility or nslookup command.</span></div>
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<span style="font-family: "arial" , "helvetica" , sans-serif; line-height: 28.7999992370605px;">Choose any website and query it twice (we will use</span><span style="font-family: "arial" , "helvetica" , sans-serif; line-height: 28.7999992370605px;"> </span><span style="border: 0px; font-family: "arial" , "helvetica" , sans-serif; font-stretch: inherit; font-style: inherit; font-variant: inherit; line-height: inherit; margin: 0px; padding: 0px; vertical-align: baseline;">facebook.com</span><span style="font-family: "arial" , "helvetica" , sans-serif; line-height: 28.7999992370605px;"> </span><span style="font-family: "arial" , "helvetica" , sans-serif; line-height: 28.7999992370605px;">as an example). Note that with dig the second time the query is completed much faster because it is being served from the cache.</span></div>
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<pre style="background: none 0px 0px repeat scroll rgb(60, 60, 60); border-radius: 4px; border: 1px solid rgb(229, 229, 229); margin-bottom: 20px; outline: 0px; overflow: auto; padding: 20px; vertical-align: baseline;"><span style="color: white;"><span style="font-size: 12px; line-height: 15.6000003814697px;">root@hackthesec:/home/hackthesec# dig facebook.com

; <<>> DiG 9.9.5-9-Ubuntu <<>> facebook.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 50459
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;facebook.com.   IN A

;; ANSWER SECTION:
facebook.com.  285 IN A 66.220.158.68

;; Query time: 65 msec
;; SERVER:192.168.1.17#53(</span></span><span style="color: white; font-size: 12px; line-height: 15.6000003814697px;">192.168.1.17</span><span style="color: white; font-size: 12px; line-height: 15.6000003814697px;">)</span>
<span style="color: white;"><span style="font-size: 12px; line-height: 15.6000003814697px;">;; WHEN: Mon Jan 25 16:59:32 IST 2016
;; MSG SIZE  rcvd: 57</span></span>
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<span style="font-family: "arial" , "helvetica" , sans-serif;"><span style="line-height: 28.7999992370605px;">You can also use </span><span style="border-image-outset: initial; border-image-repeat: initial; border-image-slice: initial; border-image-source: initial; border-image-width: initial; border: 0px; font-stretch: inherit; line-height: 28.7999992370605px; margin: 0px; padding: 0px; vertical-align: baseline;">nslookup</span><span style="line-height: 28.7999992370605px;"> to verify that the DNS server is working as expected.</span></span></div>
<pre style="background: none 0px 0px repeat scroll rgb(60, 60, 60); border-radius: 4px; border: 1px solid rgb(229, 229, 229); margin-bottom: 20px; outline: 0px; overflow: auto; padding: 20px; vertical-align: baseline;"><span style="color: white;"><span style="font-size: 12px; line-height: 15.6000003814697px;">[root@node1 ~]# nslookup facebook.com
Server:         192.168.1.17
Address:        192.168.1.17#53

Non-authoritative answer:
Name:  facebook.com
Address: 66.220.158.68</span></span></pre>
<pre style="background: none 0px 0px repeat scroll rgb(60, 60, 60); border-radius: 4px; border: 1px solid rgb(229, 229, 229); margin-bottom: 20px; outline: 0px; overflow: auto; padding: 20px; vertical-align: baseline;"><span style="color: white;"><span style="font-size: 12px; line-height: 15.6000003814697px;"><pre style="background-attachment: scroll; background-clip: initial; background-image: none; background-origin: initial; background-position: 0px 0px; background-repeat: repeat; background-size: initial; border-radius: 4px; border: 1px solid rgb(229, 229, 229); font-size: 0.9em; line-height: 1.3em; margin-bottom: 20px; outline: 0px; overflow: auto; padding: 20px; vertical-align: baseline;"><a href="http://www.hackthesec.co.in/" target="_blank">http://www.hackthesec.co.in</a>
<a href="http://www.twitter.com/hackthesecurity" target="_blank">http://www.twitter.com/hackthesecurity</a>
<span style="color: #999999;"><a href="https://www.facebook.com/htsecu">https://www.facebook.com/htsecu</a></span></pre>
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