Refer to the topology and partial configurations shown in the exhibit. The network administrator has finished configuring the NewYork and Sydney routers and issues the command ping Sydney from the NewYork router. The ping fails. What command or set of commands should the network administrator issue to correct this problem?
A. Sydney(config)# interface s0/0
Sydney(config-if)# cdp enable
B. Sydney(config)# interface s0/0
Sydney(config-if)# no shut
C. Sydney(config)# line vty 0 4
Sydney(config)# login
Sydney(config)# password Sydney
D. Sydney(config)# ip host Sydney 10.1.1.9
E. Sydney(config)# interface s0/0
Sydney(config-if)# ip address 10.1.1.5 255.255.255.252
NewYork(config)# ip host Sydney 10.1.1.5
Sorry, “ping 10.1.1.5” or “ping Sidney”
Can someone please explain to me why the answer is E? Thanks in advance.
The subnet mask in serial interface of both routers ends in 252, so its /30 wich gives space for 2 hosts, plus network and broadcast address.
The ip jumps for that subnet mask are .0, .4, .8, .16, etc
The broadcast adresses of that mask are .3, .7, 15, etc respectively.
So, if our network is .4, New York ip is .6, and the broadcast is .7, the Sidney ip should end in .5
The ip host command simply maps a name to an IP address so if you type “ip host Sydney 10.1.1.5” you can now either type “ping ip host 10.1.1.5” or “ping Sidney” and they should both work. Like a local DNS conversion.