# Cant ping to server..

**URL:** <https://forums.suse.com/t/cant-ping-to-server/28234>\
**Category:** SLES Networking\
**Created:** [June 3, 2016, 10:42am UTC](https://forums.suse.com/t/cant-ping-to-server/28234 "2016-06-03T10:42:13Z")\
**Posts on this page:** 13\
**Page:** 1

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**Author:** ![kimkhoo](https://avatars.discourse-cdn.com/v4/letter/k/0ea827/32.png) [@kimkhoo](https://forums.suse.com/u/kimkhoo)\
**Post date:** [June 3, 2016, 10:42am UTC](https://forums.suse.com/t/cant-ping-to-server/28234/1 "2016-06-03T10:42:13Z")

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Hi.

I have two nics.

eth0 - public lan  
eth1 - backup lan

when I change ip address in backup lan or eth1, I cant ping to server.

please advise where seems to be wrong.

thanks.

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**Author:** ![thsundel](https://avatars.discourse-cdn.com/v4/letter/t/13edae/32.png) [@thsundel](https://forums.suse.com/u/thsundel)\
**Post date:** [June 3, 2016, 11:02am UTC](https://forums.suse.com/t/cant-ping-to-server/28234/2 "2016-06-03T11:02:54Z")

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[QUOTE=kimkhoo;32783]Hi.

I have two nics.

eth0 - public lan  
eth1 - backup lan

when I change ip address in backup lan or eth1, I cant ping to server.

please advise where seems to be wrong.

thanks.[/QUOTE]

Can you post the output of “ip addr show” and “route -n”. From where are you pinging? Is there a firewall between the server and the “pinging machine”? How did you change the IP, through YaST or…?

Thomas

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<div class="post-metadata">

**Author:** ![kimkhoo](https://avatars.discourse-cdn.com/v4/letter/k/0ea827/32.png) [@kimkhoo](https://forums.suse.com/u/kimkhoo)\
**Post date:** [June 3, 2016, 11:21am UTC](https://forums.suse.com/t/cant-ping-to-server/28234/3 "2016-06-03T11:21:12Z")

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Hi Thomas,

Highlighted in BLUE is for backup NIC.  
In GREEN, is the public NIC.  
I am not sure if it was configured in YAST. But when I change the IP now… I used command line.  
Thanks in advance.

server1:~ # ip add show  
1: lo: \<LOOPBACK,UP,LOWER\_UP\> mtu 16436 qdisc noqueue state UNKNOWN  
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00  
inet 127.0.0.1/8 brd 127.255.255.255 scope host lo  
inet 127.0.0.2/8 brd 127.255.255.255 scope host secondary lo  
2: eth0: \<BROADCAST,MULTICAST,SLAVE,UP,LOWER\_UP\> mtu 1500 qdisc mq master bond0 state UP qlen 1000  
link/ether 90:e2:ba:4e:db:d4 brd ff:ff:ff:ff:ff:ff  
3: eth1: \<BROADCAST,MULTICAST\> mtu 1500 qdisc noop state DOWN qlen 1000  
link/ether 90:e2:ba:4e:db:d5 brd ff:ff:ff:ff:ff:ff  
4: eth2: \<BROADCAST,MULTICAST\> mtu 1500 qdisc noop state DOWN qlen 1000  
link/ether 90:e2:ba:4e:db:d6 brd ff:ff:ff:ff:ff:ff  
5: eth3: \<NO-CARRIER,BROADCAST,MULTICAST,UP\> mtu 1500 qdisc mq state DOWN qlen 1000  
link/ether 90:e2:ba:4e:db:d7 brd ff:ff:ff:ff:ff:ff  
6: eth4: \<BROADCAST,MULTICAST,SLAVE,UP,LOWER\_UP\> mtu 1500 qdisc mq master bond0 state UP qlen 1000  
link/ether 90:e2:ba:4e:db:d4 brd ff:ff:ff:ff:ff:ff  
[COLOR="#0000FF"][/COLOR][COLOR="#0000FF"]7: eth5: \<BROADCAST,MULTICAST,UP,LOWER\_UP\> mtu 1500 qdisc mq state UP qlen 1000  
link/ether 40:f2:e9:2b:75:db brd ff:ff:ff:ff:ff:ff  
inet 30.30.30.15/8 brd 30.255.255.255 scope global eth5 [/COLOR]  
8: eth6: \<BROADCAST,MULTICAST\> mtu 1500 qdisc noop state DOWN qlen 1000  
link/ether 40:f2:e9:2b:75:dc brd ff:ff:ff:ff:ff:ff  
9: eth7: \<BROADCAST,MULTICAST\> mtu 1500 qdisc noop state DOWN qlen 1000  
link/ether 40:f2:e9:2b:75:dd brd ff:ff:ff:ff:ff:ff  
[COLOR="#008000"]11: bond0: \<BROADCAST,MULTICAST,MASTER,UP,LOWER\_UP\> mtu 1500 qdisc pfifo state UP qlen 1000  
link/ether 90:e2:ba:4e:db:d4 brd ff:ff:ff:ff:ff:ff  
inet 193.18.58.35/24 brd 193.18.58.255 scope global bond0[/COLOR]  
26: usb0: \<BROADCAST,MULTICAST\> mtu 1500 qdisc noop state DOWN qlen 1000  
link/ether 42:f2:e9:2b:75:d9 brd ff:ff:ff:ff:ff:ff

server1:~ # route -n  
Kernel IP routing table  
Destination Gateway Genmask Flags Metric Ref Use Iface  
0.0.0.0 193.18.58.254 0.0.0.0 UG 0 0 0 bond0  
30.0.0.0 0.0.0.0 255.0.0.0 U 0 0 0 eth5  
127.0.0.0 0.0.0.0 255.0.0.0 U 0 0 0 lo  
193.18.58.0 0.0.0.0 255.255.255.0 U 0 0 0 bond0

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<div class="post-metadata">

**Author:** ![thsundel](https://avatars.discourse-cdn.com/v4/letter/t/13edae/32.png) [@thsundel](https://forums.suse.com/u/thsundel)\
**Post date:** [June 3, 2016, 11:41am UTC](https://forums.suse.com/t/cant-ping-to-server/28234/4 "2016-06-03T11:41:39Z")

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[QUOTE=kimkhoo;32787]Hi Thomas,

Highlighted in BLUE is for backup NIC.  
In GREEN, is the public NIC.  
I am not sure if it was configured in YAST. But when I change the IP now… I used command line.  
Thanks in advance.

server1:~ # ip add show  
1: lo: \<LOOPBACK,UP,LOWER\_UP\> mtu 16436 qdisc noqueue state UNKNOWN  
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00  
inet 127.0.0.1/8 brd 127.255.255.255 scope host lo  
inet 127.0.0.2/8 brd 127.255.255.255 scope host secondary lo  
2: eth0: \<BROADCAST,MULTICAST,SLAVE,UP,LOWER\_UP\> mtu 1500 qdisc mq master bond0 state UP qlen 1000  
link/ether 90:e2:ba:4e:db:d4 brd ff:ff:ff:ff:ff:ff  
3: eth1: \<BROADCAST,MULTICAST\> mtu 1500 qdisc noop state DOWN qlen 1000  
link/ether 90:e2:ba:4e:db:d5 brd ff:ff:ff:ff:ff:ff  
4: eth2: \<BROADCAST,MULTICAST\> mtu 1500 qdisc noop state DOWN qlen 1000  
link/ether 90:e2:ba:4e:db:d6 brd ff:ff:ff:ff:ff:ff  
5: eth3: \<NO-CARRIER,BROADCAST,MULTICAST,UP\> mtu 1500 qdisc mq state DOWN qlen 1000  
link/ether 90:e2:ba:4e:db:d7 brd ff:ff:ff:ff:ff:ff  
6: eth4: \<BROADCAST,MULTICAST,SLAVE,UP,LOWER\_UP\> mtu 1500 qdisc mq master bond0 state UP qlen 1000  
link/ether 90:e2:ba:4e:db:d4 brd ff:ff:ff:ff:ff:ff  
[COLOR="#0000FF"][/COLOR][COLOR="#0000FF"]7: eth5: \<BROADCAST,MULTICAST,UP,LOWER\_UP\> mtu 1500 qdisc mq state UP qlen 1000  
link/ether 40:f2:e9:2b:75:db brd ff:ff:ff:ff:ff:ff  
inet 30.30.30.15/8 brd 30.255.255.255 scope global eth5 [/COLOR]  
8: eth6: \<BROADCAST,MULTICAST\> mtu 1500 qdisc noop state DOWN qlen 1000  
link/ether 40:f2:e9:2b:75:dc brd ff:ff:ff:ff:ff:ff  
9: eth7: \<BROADCAST,MULTICAST\> mtu 1500 qdisc noop state DOWN qlen 1000  
link/ether 40:f2:e9:2b:75:dd brd ff:ff:ff:ff:ff:ff  
[COLOR="#008000"]11: bond0: \<BROADCAST,MULTICAST,MASTER,UP,LOWER\_UP\> mtu 1500 qdisc pfifo state UP qlen 1000  
link/ether 90:e2:ba:4e:db:d4 brd ff:ff:ff:ff:ff:ff  
inet 193.18.58.35/24 brd 193.18.58.255 scope global bond0[/COLOR]  
26: usb0: \<BROADCAST,MULTICAST\> mtu 1500 qdisc noop state DOWN qlen 1000  
link/ether 42:f2:e9:2b:75:d9 brd ff:ff:ff:ff:ff:ff

server1:~ # route -n  
Kernel IP routing table  
Destination Gateway Genmask Flags Metric Ref Use Iface  
0.0.0.0 193.18.58.254 0.0.0.0 UG 0 0 0 bond0  
30.0.0.0 0.0.0.0 255.0.0.0 U 0 0 0 eth5  
127.0.0.0 0.0.0.0 255.0.0.0 U 0 0 0 lo  
193.18.58.0 0.0.0.0 255.255.255.0 U 0 0 0 bond0[/QUOTE]

And when you say you can’t ping the server then I assume you ping this IP 30.30.30.15? From where are you trying to ping, is that device on the same network range as 30.30.30.15/8?

Thomas

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<div class="post-metadata">

**Author:** ![kimkhoo](https://avatars.discourse-cdn.com/v4/letter/k/0ea827/32.png) [@kimkhoo](https://forums.suse.com/u/kimkhoo)\
**Post date:** [June 3, 2016, 11:45am UTC](https://forums.suse.com/t/cant-ping-to-server/28234/5 "2016-06-03T11:45:21Z")

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Hi Thomas,

Thanks for quick reply.  
Am ping from another server that is on different network segment.

I ping by hostname… # ping server1

If no change in eth5 \*(backup NIC), I can ping. It will return with hostname and ipaddress 193.18.58.35.

Once I change backup ip add, I cant ping using hostname and ip add at all.

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<div class="post-metadata">

**Author:** ![thsundel](https://avatars.discourse-cdn.com/v4/letter/t/13edae/32.png) [@thsundel](https://forums.suse.com/u/thsundel)\
**Post date:** [June 3, 2016, 11:59am UTC](https://forums.suse.com/t/cant-ping-to-server/28234/6 "2016-06-03T11:59:12Z")

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[QUOTE=kimkhoo;32789]Hi Thomas,

Thanks for quick reply.  
Am ping from another server that is on different network segment.

I ping by hostname… # ping server1

If no change in eth5 \*(backup NIC), I can ping. It will return with hostname and ipaddress 193.18.58.35.

Once I change backup ip add, I cant ping using hostname and ip add at all.[/QUOTE]

After you change the ip of eth5, post the output of “ip addr show” and “route -n”.

Thomas

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<div class="post-metadata">

**Author:** ![kimkhoo](https://avatars.discourse-cdn.com/v4/letter/k/0ea827/32.png) [@kimkhoo](https://forums.suse.com/u/kimkhoo)\
**Post date:** [June 3, 2016, 12:10pm UTC](https://forums.suse.com/t/cant-ping-to-server/28234/7 "2016-06-03T12:10:38Z")

</div>

Hi Thomas,

server1:~ # ifconfig eth5 172.29.50.52  
server1:~ # route -n  
Kernel IP routing table  
Destination Gateway Genmask Flags Metric Ref Use Iface  
0.0.0.0 193.18.58.254 0.0.0.0 UG 0 0 0 bond0  
127.0.0.0 0.0.0.0 255.0.0.0 U 0 0 0 lo  
172.29.0.0 0.0.0.0 255.255.0.0 U 0 0 0 eth5  
193.18.58.0 0.0.0.0 255.255.255.0 U 0 0 0 bond0  
server1:~ # ip add show  
1: lo: \<LOOPBACK,UP,LOWER\_UP\> mtu 16436 qdisc noqueue state UNKNOWN  
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00  
inet 127.0.0.1/8 brd 127.255.255.255 scope host lo  
inet 127.0.0.2/8 brd 127.255.255.255 scope host secondary lo  
2: eth0: \<BROADCAST,MULTICAST,SLAVE,UP,LOWER\_UP\> mtu 1500 qdisc mq master bond0 state UP qlen 1000  
link/ether 90:e2:ba:4e:db:d4 brd ff:ff:ff:ff:ff:ff  
3: eth1: \<BROADCAST,MULTICAST\> mtu 1500 qdisc noop state DOWN qlen 1000  
link/ether 90:e2:ba:4e:db:d5 brd ff:ff:ff:ff:ff:ff  
4: eth2: \<BROADCAST,MULTICAST\> mtu 1500 qdisc noop state DOWN qlen 1000  
link/ether 90:e2:ba:4e:db:d6 brd ff:ff:ff:ff:ff:ff  
5: eth3: \<NO-CARRIER,BROADCAST,MULTICAST,UP\> mtu 1500 qdisc mq state DOWN qlen 1000  
link/ether 90:e2:ba:4e:db:d7 brd ff:ff:ff:ff:ff:ff  
6: eth4: \<BROADCAST,MULTICAST,SLAVE,UP,LOWER\_UP\> mtu 1500 qdisc mq master bond0 state UP qlen 1000  
link/ether 90:e2:ba:4e:db:d4 brd ff:ff:ff:ff:ff:ff  
[COLOR="#0000FF"]7: eth5: \<BROADCAST,MULTICAST,UP,LOWER\_UP\> mtu 1500 qdisc mq state UP qlen 1000  
link/ether 40:f2:e9:2b:75:db brd ff:ff:ff:ff:ff:ff  
inet 172.29.50.52/16 brd 172.29.255.255 scope global eth5[/COLOR]  
8: eth6: \<BROADCAST,MULTICAST\> mtu 1500 qdisc noop state DOWN qlen 1000  
link/ether 40:f2:e9:2b:75:dc brd ff:ff:ff:ff:ff:ff  
9: eth7: \<BROADCAST,MULTICAST\> mtu 1500 qdisc noop state DOWN qlen 1000  
link/ether 40:f2:e9:2b:75:dd brd ff:ff:ff:ff:ff:ff  
11: bond0: \<BROADCAST,MULTICAST,MASTER,UP,LOWER\_UP\> mtu 1500 qdisc pfifo state UP qlen 1000  
link/ether 90:e2:ba:4e:db:d4 brd ff:ff:ff:ff:ff:ff  
inet 193.18.58.35/24 brd 193.18.58.255 scope global bond0  
26: usb0: \<BROADCAST,MULTICAST\> mtu 1500 qdisc noop state DOWN qlen 1000  
link/ether 42:f2:e9:2b:75:d9 brd ff:ff:ff:ff:ff:ff

---

<div class="post-metadata">

**Author:** ![thsundel](https://avatars.discourse-cdn.com/v4/letter/t/13edae/32.png) [@thsundel](https://forums.suse.com/u/thsundel)\
**Post date:** [June 3, 2016, 2:23pm UTC](https://forums.suse.com/t/cant-ping-to-server/28234/8 "2016-06-03T14:23:28Z")

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[QUOTE=kimkhoo;32791]Hi Thomas,

server1:~ # ifconfig eth5 172.29.50.52  
server1:~ # route -n  
Kernel IP routing table  
Destination Gateway Genmask Flags Metric Ref Use Iface  
0.0.0.0 193.18.58.254 0.0.0.0 UG 0 0 0 bond0  
127.0.0.0 0.0.0.0 255.0.0.0 U 0 0 0 lo  
172.29.0.0 0.0.0.0 255.255.0.0 U 0 0 0 eth5  
193.18.58.0 0.0.0.0 255.255.255.0 U 0 0 0 bond0  
server1:~ # ip add show  
1: lo: \<LOOPBACK,UP,LOWER\_UP\> mtu 16436 qdisc noqueue state UNKNOWN  
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00  
inet 127.0.0.1/8 brd 127.255.255.255 scope host lo  
inet 127.0.0.2/8 brd 127.255.255.255 scope host secondary lo  
2: eth0: \<BROADCAST,MULTICAST,SLAVE,UP,LOWER\_UP\> mtu 1500 qdisc mq master bond0 state UP qlen 1000  
link/ether 90:e2:ba:4e:db:d4 brd ff:ff:ff:ff:ff:ff  
3: eth1: \<BROADCAST,MULTICAST\> mtu 1500 qdisc noop state DOWN qlen 1000  
link/ether 90:e2:ba:4e:db:d5 brd ff:ff:ff:ff:ff:ff  
4: eth2: \<BROADCAST,MULTICAST\> mtu 1500 qdisc noop state DOWN qlen 1000  
link/ether 90:e2:ba:4e:db:d6 brd ff:ff:ff:ff:ff:ff  
5: eth3: \<NO-CARRIER,BROADCAST,MULTICAST,UP\> mtu 1500 qdisc mq state DOWN qlen 1000  
link/ether 90:e2:ba:4e:db:d7 brd ff:ff:ff:ff:ff:ff  
6: eth4: \<BROADCAST,MULTICAST,SLAVE,UP,LOWER\_UP\> mtu 1500 qdisc mq master bond0 state UP qlen 1000  
link/ether 90:e2:ba:4e:db:d4 brd ff:ff:ff:ff:ff:ff  
[COLOR="#0000FF"]7: eth5: \<BROADCAST,MULTICAST,UP,LOWER\_UP\> mtu 1500 qdisc mq state UP qlen 1000  
link/ether 40:f2:e9:2b:75:db brd ff:ff:ff:ff:ff:ff  
inet 172.29.50.52/16 brd 172.29.255.255 scope global eth5[/COLOR]  
8: eth6: \<BROADCAST,MULTICAST\> mtu 1500 qdisc noop state DOWN qlen 1000  
link/ether 40:f2:e9:2b:75:dc brd ff:ff:ff:ff:ff:ff  
9: eth7: \<BROADCAST,MULTICAST\> mtu 1500 qdisc noop state DOWN qlen 1000  
link/ether 40:f2:e9:2b:75:dd brd ff:ff:ff:ff:ff:ff  
11: bond0: \<BROADCAST,MULTICAST,MASTER,UP,LOWER\_UP\> mtu 1500 qdisc pfifo state UP qlen 1000  
link/ether 90:e2:ba:4e:db:d4 brd ff:ff:ff:ff:ff:ff  
inet 193.18.58.35/24 brd 193.18.58.255 scope global bond0  
26: usb0: \<BROADCAST,MULTICAST\> mtu 1500 qdisc noop state DOWN qlen 1000  
link/ether 42:f2:e9:2b:75:d9 brd ff:ff:ff:ff:ff:ff[/QUOTE]

That looks okay to me… strange… The server you are pinging from, is it on the 172.29.0.0 0.0.0.0 255.255.0.0 network?

Thomas

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<div class="post-metadata">

**Author:** ![ab1](https://avatars.discourse-cdn.com/v4/letter/a/d2c977/32.png) [@ab1](https://forums.suse.com/u/ab1)\
**Post date:** [June 3, 2016, 5:40pm UTC](https://forums.suse.com/t/cant-ping-to-server/28234/9 "2016-06-03T17:40:18Z")

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How does your pinging machine get the IP address of the server? If from  
DNS, are you updating DNS at the same time that you change the server’s IP  
address? If not from DNS, are you updating the /etc/hosts file at the  
same time that you change the server’s IP address?

Pinging is a network layer (layer 3) test, so stick with layer three  
addresses (IPs) and test that. If that works, then move over to try  
application layer (layer seven) tests by verifying DNS is setup correctly.  
Avoid merely using hostnames; they are not reliable and are too-dependent  
on where your computer is, if they have a search list setup, etc.

–  
Good luck.

If you find this post helpful and are logged into the web interface,  
show your appreciation and click on the star below…

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<div class="post-metadata">

**Author:** ![Jens-U](https://avatars.discourse-cdn.com/v4/letter/j/d78d45/32.png) [@Jens-U](https://forums.suse.com/u/Jens-U)\
**Post date:** [June 6, 2016, 1:40pm UTC](https://forums.suse.com/t/cant-ping-to-server/28234/10 "2016-06-06T13:40:35Z")

</div>

Hi kimkhoo,

if I understand your situation right, you’re always pinging the “public” IP address of the server in question, while changing the IP address on the “backup” interface.

One possible reason that pinging the server from your test machine breaks after changing the backup interface IP, is that the ping response, sent by the server, goes out the backup interface. The most likely reason for this would be that the pinging test machine uses a source IP address from the same subnet range as the backup interface of your server (172.29.0.0/16).

Regards,  
J

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<div class="post-metadata">

**Author:** ![Jens-U](https://avatars.discourse-cdn.com/v4/letter/j/d78d45/32.png) [@Jens-U](https://forums.suse.com/u/Jens-U)\
**Post date:** [June 6, 2016, 1:43pm UTC](https://forums.suse.com/t/cant-ping-to-server/28234/11 "2016-06-06T13:43:12Z")

</div>

Oh, I forgot to mention:

“The most likely reason for this would be that the pinging test machine uses a source IP address from the same subnet range as the backup interface of your server (172.29.0.0/16).” … and that the VLAN / physical Ethernet segment that the backup interface is connected to, has no direct connection to the test machine sending the pings.

IOW, if the “backup network” is isolated, but using an IP address range that is already used elsewhere, machine connected to the “elsewhere” network will not be able to see IP replies from the server.

Regards,  
Jens

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<div class="post-metadata">

**Author:** ![kimkhoo](https://avatars.discourse-cdn.com/v4/letter/k/0ea827/32.png) [@kimkhoo](https://forums.suse.com/u/kimkhoo)\
**Post date:** [June 13, 2016, 10:34am UTC](https://forums.suse.com/t/cant-ping-to-server/28234/12 "2016-06-13T10:34:26Z")

</div>

Yes. It is on the same subnet…

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<div class="post-metadata">

**Author:** ![Jens-U](https://avatars.discourse-cdn.com/v4/letter/j/d78d45/32.png) [@Jens-U](https://forums.suse.com/u/Jens-U)\
**Post date:** [June 13, 2016, 12:41pm UTC](https://forums.suse.com/t/cant-ping-to-server/28234/13 "2016-06-13T12:41:21Z")

</div>

…and is it on the same physical network segment (or to be more precise, in the same layer 2 broadcast domain)?