How to find default gateway? (packet tracer activity)

[Theminecraftaddict555]

So here is the address table and it wants me to fill in the missing parts

http://imgur.com/a/0Gglz

 

and the topology to show the idea of what is going on: http://imgur.com/a/MUKTa

 

How the heck do I find the missing default gateway from the info listed from the addressing table and topology? The devices in the topology doesn't show what the default gateway addresses especially the router

[Clyne]

Whatever interface that the PC/Switch connects to the router is the default gateway...

 

[Oshino Shinobu]

172.14.5.1 and 172.14.10.1 should be the default gateways, depending on which subnet the devices are on. (so, for 172.14.5.x, it's 172.14.5.1 and for 172.14.10.x devices, it's 172.14.10.1). 

 

The router will be the default gateway (router is called College). The router appears to have two subnets, one with the class C address range of 172.14.10.x and the other with the class C address range 172.14.5.x. 

[LAwLz]

Default gateways:

Class-A 172.14.5.1

Class-B 172.14.10.1

Student-1 172.14.5.1

Student-2 172.14.5.1

Student-3 172.14.10.1

Student-4 172.14.10.1

 

 

What you do is you look at which network each device is on. For example Student-2 is on the network 172.14.5.X (because the subnet mask is 255.255.255.0 but subnetting might be beyond this assignment).

 

What address does the interface on the router (called college) have which is also on the 172.14.5.X network? Well, if we look at the table we can see that College's interface named G0/0 is in that network, and it has the IP 172.14.5.1. So there's your answer.

 

 

Your default gateway is the router that is the closest to you. In this case it's the router called College (which has two different interfaces, so you need to look up which interface goes to which PC).

[Falconevo]

The gateway can literally be any number within the /24 subnet.  It's totally up to you or the previous person who configured it wanted to select.  Most sensible people will either select the bottom of the IP /24 which would be 172.14.*.1 or the top of the /24 subnet which would be 172.14.*.254.

 

Is this an already in place configuration?  If so just plug in a device on each network segment and hope that someone configured DHCP which should provide you with a gateway IP.  Would probably clear things up for you.

 

[LAwLz]

3 hours ago, Falconevo said:

The gateway can literally be any number within the /24 subnet.  It's totally up to you or the previous person who configured it wanted to select.  Most sensible people will either select the bottom of the IP /24 which would be 172.14.*.1 or the top of the /24 subnet which would be 172.14.*.254.

 

Is this an already in place configuration?  If so just plug in a device on each network segment and hope that someone configured DHCP which should provide you with a gateway IP.  Would probably clear things up for you.

Look at the topology and the table (the imgur links). It gives you all the info needed to figure out which IP address is the default gateway.

[Falconevo]

33 minutes ago, LAwLz said:

Look at the topology and the table (the imgur links). It gives you all the info needed to figure out which IP address is the default gateway.

The default gateway is specified by who ever set up the network and not by the class of the network, anyone can set what ever I want to be the gateway.  Logically people dont and they generally use the lower or upper octet in the IP range.

There is literally nothing stopping people from setting the gateway IP to 172.14.*.133 if that's what the network engineer wanted to do.  People rarely do it, but it certainly a possibility as I have seen it in the field before.

[LAwLz]

9 minutes ago, Falconevo said:

The default gateway is specified by who ever set up the network and not by the class of the network, anyone can set what ever I want to be the gateway.  Logically people dont and they generally use the lower or upper octet in the IP range.

There is literally nothing stopping people from setting the gateway IP to 172.14.*.133 if that's what the network engineer wanted to do.  People rarely do it, but it certainly a possibility as I have seen it in the field before.

Dude... Look at the topology and IP table in the post. Sure you could set it to end with 133 if you want, but if you look at the links we can see that they didn't. We have the IP address for the router interfaces already. We don't need to plug anything in, or hope that someone has configured a DHCP, because we already have all the info we need.

[Falconevo]

On 20/01/2017 at 7:02 PM, LAwLz said:

Dude... Look at the topology and IP table in the post. Sure you could set it to end with 133 if you want, but if you look at the links we can see that they didn't. We have the IP address for the router interfaces already. We don't need to plug anything in, or hope that someone has configured a DHCP, because we already have all the info we need.

Yea my bad, I didn't even see the first img link.