why multiple messages from kernel

[Surendranath <suren@xxxxxxxxxxxxx>]

Hi,
Please clarify my doubt.

I have created a RAW socket with domain PF_ROUTE and protocol NETLINK_ROUTE.
I am doing select on this socket to listen any Route and Interface related
messages from
kernel.

Then I modified my system IP address to 172.16.9.74 (subnet mask
255.255.255.0, bcast 172.16.9.255)
from 172.16.8.74 ( subnet mask 255.255.255.0, bcast 172.16.8.255)  using
ifconfig command.

I got messages from kernel like this.

1. Delete IF address 172.16.8.74  on eth0
2. New IF address   172.16.9.74   on eth0
3. New Route entry  172.16.9.70  
4. New Route entry  172.16.255.255  (gateway 172.16.9.74)
5. New Route entry  172.16.0.0  (gateway 172.16.9.74)
6. New Route entry  172.16.0.0  (gateway 172.16.9.74)

7. Delete IF address 172.16.9.74  on eth0    (Note this : deletion of new
address)  
8. New IF address   172.16.9.74   on eth0
9. New Route entry  172.16.9.70  
10. New Route entry  172.16.255.255  (gateway 172.16.9.74)
11. New Route entry  172.16.9.0  (gateway 172.16.9.74)
12. New Route entry  172.16.9.255  (gateway 172.16.9.74)

13. Delete IF address 172.16.9.74  on eth0
14. New IF address   172.16.9.74   on eth0
15. New Route entry  172.16.9.70  
16. New Route entry  172.16.9.0  (gateway 172.16.9.74)
17. New Route entry  172.16.9.255  (gateway 172.16.9.74)

I could not understand, Why These many messages(most of them duplicates)
from kernel? 
Why IF address deletion for my new address 172.16.9.74,  and again
Reassignment?
I didnot get any Route entry deletion for my old address 172.16.8.74.
Why this is happening?  I am using redhat  kernel version 2.2.14.

Thanks
suren.