DNS Exercise 1.1

1. Configure the resolver on your workstation

Create /etc/resolv.conf containing:

domain ws.linuxchix.or.ke
nameserver 196.216.76.252

2. Issue DNS queries using 'dig'

2a. Run each command, look for the ANSWER section and write down the
result. Make a note the TTL as well. 

Repeat the command. Is the TTL the same?

Are the responses Authoritative?
                                           				RESULT
                                           				-----------
# dig www.tiscali.co.uk. a

# dig afnog.org. mx

# dig news.bbc.co.uk. a
                
# dig <domain of your choice> a
                         
# dig <domain of your choice> mx

# dig tiscali.co.uk. txt

# dig ripe.net. txt

# dig geek.tiscali.co.uk. a

2b. Now send some queries to another caching server. How long did it take each answer to be received?

# dig @158.152.1.58 news.bbc.co.uk. a

# dig @isp1.4u.com.gh. yahoo.com. a

# dig @<a server of your choice> <domain of your choice> a


3. Reverse DNS lookups

Now try some reverse DNS lookups. Remember to reverse the four parts of
the IP address, add '*.in-addr.arpa.*', and ask for a *PTR* resource record.

(For 196.216.76.252)
# dig 252.76.216.196.in-addr.arpa. ptr

Repeat for an IP address of your choice.

Now try the short form of dig using the '-x' flag for reverse lookups:

# dig -x 196.216.76.252

# dig @<server of your choice> -x <IP address of your choice>

4. Use tcpdump to show DNS traffic

In a separate window, run the following command (you must be 'root')

# tcpdump -n -s 1500 -i sis0 udp port 53

This shows all packets going in and out of your machine for UDP port 53
(DNS). Now go to another window and repeat some of the 'dig' queries
from earlier. Look at the output of tcpdump, check the source and
destination IP address of each packet

-n
Prevents tcpdump doing reverse DNS lookups on the packets it receives, which would generate additional (confusing) DNS traffic 

-s 1500
Read the entire packet (otherwise tcpdump only reads the headers)
 
-i sis0
Which interface to listen on (use ifconfig to determine the name of your ethernet interface)

udp port 53
    A filter which matches only packets to/from UDP port 53