Starting today, I will be doing  Incident Management. This is not because I was demoted, it is more of giving a chance for other people in the team to experience handling Change Management.

Anyway, there was a critical incident regarding a box that was inaccessible to both ssh and telnet. So, I connect to the box via console and checked LAN / NIC Interfaces using the commands below:

Show available NIC and its corresponding IP Address:

# netstat -in
Name Mtu Network Address Ipkts Ierrs Opkts Oerrs Coll
lan0 1500 155.125.169.0 155.125.169.12 38900103 0 2276603690 0 0
lo0 4136 127.0.0.0 127.0.0.1 20049568 0 20050074 0 0
lan6 1500 155.125.170.0 155.125.170.28 3159721067 0 3420341 0 0

Show status of LAN interfaces:

# ifconfig lan0
lan0: flags=1843<UP,BROADCAST,RUNNING,MULTICAST,CKO>
inet 155.125.169.12 netmask ffffff00 broadcast 155.125.169.255

# ifconfig lan6
lan6: flags=1843<UP,BROADCAST,RUNNING,MULTICAST,CKO>
inet 155.125.170.28 netmask ffffff00 broadcast 155.125.255.255

It seems that the LAN cards are working fine, so I did a quick nslookup of the said box using command # nslookup hostname

It was as I expected, the problem was on the DNS entry of the box. Someone updated the DNS mapping ahead of scheduled change.

Forwarded the incident ticket to the proper group.