Page 126 - DCAP602_NETWORK_OPERATING_SYSTEMS_I

Network Operating Systems-I

notes The client will now be installed and the suitable configuration file like the ones shown above will
be created. Even though the file was created for you, we showed you the typical files for both
dyndns.org and EasyDNS services in case you need to edit them at a later point. If you want to
examine your config file you can do so using the nano text editor with the command:
nano /etc/ddclient.conf
If you’re using a modem connection you’ll want to initial connect to your ISP with the pon
command. If you didn’t set ddclient to run as a daemon then just type in:

ddclient
at the shell prompt once you’re connected. The resulting memo will tell you what IP address
your external interface has (and what the DNS record will be updated with.

As mentioned previously, it will take awhile for this update to take affect. To see if it has taken
affect yet, try pinging using your domain name and see if the returned IP address matches what
was indicated in the message when you started ddclient.

!
Caution If you used the above ping command in the background to keep your connection
up you can still issue a second ping command in the foreground to check the returned IP
address.

6.1.4 other Dns server files

Given that a DNS server can host the zone files for lots of different domains, each having two
zone files, it needs a way to tell which zone files are for which domains. It does this in the named.
conf file which, like the zone files themselves, is located in the /etc/bind directory (which you’ll
see when we install Bind shortly).
Of the two zone files for each domain the one we’ve been talking about all along has been for
forward lookups (resolving names to IP addresses). This zone file is usually named db.my-last-
name.net.

DNS also offers a “reverse lookup” function that allows you to decode IP addresses to host/
domain names. The information that allows this to happen is stored in the second zone file.
Here’s a reverse-lookup zone file that corresponds to the simpler zone file we showed earlier:

$TTL 86400
1.168.192.in-addr.arpa. IN SOA ns1.easydns.com. \
me.my-name.com. (
2004011522 ; Serial no., based on date
21600 ; Refresh after 6 hours
3600 ; Retry after 1 hour
604800 ; Expire after 7 days

3600 ; Minimum TTL of 1 hour
)
51 IN PTR debian
@ IN NS ns1.easydns.com.
@ IN NS ns2.easydns.com.

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