0

This is a network setup in a lab of academic institution PC1: Connected to wired LAN socket of Lab. Connection is DHCP.

IP: 10.21.106.221
Netmask: 255.255.252.0
Default Route: 10.21.107.254
Broadcast: 10.21.107.255
Primary DNS: 10.24.0.193
Secondary DNS: 10.24.0.194
IP shown on www.whatismyip.com: 14.139.160.237

A wireless router is connected to another LAN socket of the same lab (hopefully of same network). IP allotted to router through DHCP is

IP: 10.21.106.76
Netmask: 255.255.252.0
Default Gateway: 10.21.107.254
DHCP Server : 10.24.4.7
DNS Server : 10.24.0.193, 10.24.0.194

Router LAN settings are

Router IP: 10.0.0.1
Netmask: 255.255.255.0

PC2 is getting internet through wireless router. IP settings received by PC2 are

ip: 10.0.0.7
Mask: 255.255.255.0
Gateway: 10.0.0.1
IP shown on www.whatismyip.com: 14.139.160.242

As per my understanding, I should see the same ip on www.whatismyip.com from both PC, but this is not the case here.

closed as off-topic by user36472, Ron Maupin May 29 '18 at 13:54

This question appears to be off-topic. The users who voted to close gave this specific reason:

  • "NE is a site for to ask and provide answers about professionally managed networks in a business environment. Your question falls outside the areas our community decided are on topic. Please visit the help center for more details. If you disagree with this closure, please ask on Network Engineering Meta." – Community, Ron Maupin
If this question can be reworded to fit the rules in the help center, please edit the question.

  • 1
    Unfortunately, questions about networks not under your direct control are off-topic here. – Ron Maupin May 29 '18 at 13:54
2

An academic institution is typically large enough to have several outgoing firewalls if not Internet connections. This particular institution appears to have a /24 of public address space.

It appears that this one sends wireless traffic out of a different interface than wired. This is not unusual: either for simple convenience or for prioritising bandwidth for a given set of users.

Sometimes you see networks where the outgoing IP address changes per connection, or is different for UDP and TCP. It's all up to the whim of what the controller of the network thinks is a good idea, usually for bandwidth management, anti-abuse, and security purposes.

  • Thanks for your answer. I don't have good knowledge of networking but I get your point to some extent. Is there any method/command to know what range of local IPs will correspond to same public ip? – Ravi May 29 '18 at 13:19
  • 1
    No, it's just whatever those in charge of a network have chosen. – jonathanjo May 29 '18 at 13:46

Not the answer you're looking for? Browse other questions tagged or ask your own question.