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I just installed CentOS 7 and configured my network as given here

When I did cat /etc/resolv.conf, I got:

# Generated by NetworkManager
search home
nameserver <IP address>

So I guess I have only one DNS and included only DNS1="" in the /etc/sysconfig/network-scripts/ifcfg-enp5s0 file.

When I do route -n, I get:

Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         <IP Address-1>      0.0.0.0         UG    100    0        0 enp5s0
<IP Address-2>      0.0.0.0         255.255.255.0   U     100    0        0 enp5s0

I am assuming my gateway is IP Address-1 above and updated the same in config file. Now my /etc/sysconfig/network-scripts/ifcfg-enp5s0 looks like:

TYPE="Ethernet"
BOOTPROTO="dhcp"
DEFROUTE="yes"
PEERDNS="yes"
PEERROUTES="yes"
IPV4_FAILURE_FATAL="no"
IPV6INIT="yes"
IPV6_AUTOCONF="yes"
IPV6_DEFROUTE="yes"
IPV6_PEERDNS="yes"
IPV6_PEERROUTES="yes"
IPV6_FAILURE_FATAL="no"
NAME="enp5s0"
UUID="ae988f3f-1fdb-4613-a7bc-c43fb8076c15"
DEVICE="enp5s0"
ONBOOT="yes"
IPADDR="172.XX.X.XX"
PREFIX="24"
GATEWAY="172.XX.X.X"
DNS1="172.XX.X.X" 
DNS2="172.XX.X.X"

Both DNS1, DNS2 are same as Gateway.

My /etc/resolv.conf looks like: # Generated by NetworkManager domain hom search home nameserver 172.XX.X.X

After updating all these values and naming my machine centos7 in /etc/hostname file, I am not able to connect to the machine with ssh user_name@hostname but ssh user_name@172.XX.X.XX works. Also, after the machine logs in, the prompt looks like: [user_name@hostname ~]$

We do have other machines running Centos 6 and donot have such issues. We use host names for remote connection to those. I am having this problem only with centOS 7. Also, when i do host <IP ADDRESS>, all other machines show their hostnames but Centos 7 doesnot. It just says new-host-23.home

Not sure if this is a machine issue or a DNS issue. I did not find my solution in another similar question on Stack overflow. Someone please help me.

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  • are you able to ping centos7?
    – sebastienvg
    Jul 27, 2016 at 20:33

2 Answers 2

Reset to default
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First, make sure if the following value is correct:

domain hom

Then, perform a simple network test on your SSH client machine:

nslookup <centos7_hostname>

A positive result should be similar as follow:

Non-authoritative answer:
Name:    www.google.com
Addresses:  216.58.221.100

If you cannot get a successful response from NSLOOKUP, you need to check if a relevant DNS record is stored at your local DNS server.

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  • Thanks, I got something strange here: nslookup <centos7_hostname> gives: Name: centos7 Address 1: some other IP Address. the IP Address I am getting here is not what I see when I do ifconfig on the centos7 machine.
    – kskp
    Jul 28, 2016 at 14:43
  • Then you have to check the record of your DNS server to see if it is pointed to the correct IP address.
    – Simon MC. Cheng
    Jul 29, 2016 at 2:21
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You have put:

BOOTPROTO="dhcp"

But it should be:

BOOTPROTO="none"

With your config, you are still using DHCP, so it is not strange that you get another IP... because your IP settings is ignored.

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