routing table question

 
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Operating Systems Linux Red Hat routing table question
# 1  
Old 03-05-2010
routing table question

I have below routing table in linux kernel 2.6.9
Code:
[root@TSTgcota ~]# netstat -rn
Kernel IP routing table
Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface
10.155.24.0     0.0.0.0         255.255.252.0   U         0 0          0 eth0
169.254.0.0     0.0.0.0         255.255.0.0     U         0 0          0 eth0
0.0.0.0         10.155.24.1     0.0.0.0         UG        0 0          0 eth0

If the packet go to 169.254.1.1 , which road od it go ??Where does it destined??
If the packet go to 10.155.24.10 , which road it go ?? where does it destined??
If the packet go to 1.1.1.1 which road it go ?? where does it destined ????
Please advice .

Last edited by pludi; 03-05-2010 at 04:40 AM.. Reason: code tags, please...
# 2  
Old 03-05-2010
What ever packet u send it will hit 10.155.24.1 first .

For the path you can use "traceroute"

Code:
traceroute 10.155.24.10

# 3  
Old 03-05-2010
Quote:
Originally Posted by amitranjansahu
What ever packet u send it will hit 10.155.24.1 first .

For the path you can use "traceroute"

Code:
traceroute 10.155.24.10


So, is it 0.0.0.0 mean any IP address or destined address ??
So, can I remove below two entries ??
Code:
 
10.155.24.0     0.0.0.0         255.255.252.0   U         0 0          0 eth0
169.254.0.0     0.0.0.0         255.255.0.0     U         0 0          0 eth0

As the entry start 0.0.0.0 already represent all IP route to 10.155.24.1 ??
Please advice ....
# 4  
Old 03-05-2010
I think you're not quite sure what the entrances in your routing table stands for, so lets take them step by step.
Code:
10.155.24.0     0.0.0.0         255.255.252.0   U         0 0          0 eth0

is telling that your eth0 is assigned an IP address within the 10.155.24.0 address range with a subnet matching 255.255.252.0
Code:
169.254.0.0     0.0.0.0         255.255.0.0     U         0 0          0 eth0

is the default address space where the interface assumes to have an IP within should the dhcp request fail, this can be removed since we assume the dhcp request would never fail.
Code:
0.0.0.0         10.155.24.1     0.0.0.0         UG        0 0          0 eth0

This is the default route "UG" telling that anything the machine wants to reached should be asked for at the IP 10.155.24.1, conveniently it is matching the address space provided to your interface.
# 5  
Old 03-09-2010
HI,
How can you know which route is for DHCP ,which route is for other as
the first two route look like the same apart from the different IP 10.155.24 /169.254.9... ..
Could you advice how you can recongise/differentiate them????
Code:
 
10.155.24.0     0.0.0.0         255.255.252.0   U         0 0          0 eth0
169.254.0.0     0.0.0.0         255.255.0.0     U         0 0          0 eth0

# 6  
Old 03-09-2010
The network 169.254.0.0/16 is a specialized IP range defined in RFC 3330: This is the "link local" block. It is allocated for communication between hosts on a single link. Hosts obtain these addresses by auto-configuration, such as when a DHCP server may not be found.
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