If you do a lot of telnetting in your lab, you could set up an internal DNS server to be able to use router names instead of IP addresses.

Select a router that will act as the DNS server and configure it on all other routers in your lab. For example, if your DNS server has IP address 10.0.0.1, use the following configuration commands:

ip domain-lookup
ip name-server 10.0.0.1

On the DNS server, disable DNS lookup and DNS forwarding (it has nowhere else to go) and define all the routers as IP host names:

no ip domain lookup
!
ip dns view default
 no dns forwarding
!
ip dns server
!
ip host Core-1 10.0.0.1
ip host Core-2 10.0.0.2
ip host POP 192.168.2.1
ip host Ext 192.168.1.5
ip name-server 10.0.0.1

If you also define IP addresses for the WAN links, for example:

ip host serial-1-0.X1 10.0.1.6
ip host serial-1-0.Core-1 10.0.1.1

… you'll get correct hop-by-hop information from the traceroute command:

POP#trace Ext
Translating "Ext"...domain server (10.0.0.1) [OK]
Type escape sequence to abort.
Tracing the route to Ext (192.168.1.5)
  1 serial-1-0.Core-1 (10.0.1.1) 36 msec 24 msec 16 msec
  2 serial-1-0.X1 (10.0.1.6) 24 msec 28 msec 4 msec
  3 Ext (192.168.1.5) 20 msec * 24 msec