NAT Practice Questions

Answers and explanations appear when you work through the set above.

1. Which command creates a permanent one to one static NAT mapping between an internal private address and a public address?

   • ip nat inside source static 172.16.0.1 100.0.0.1
   • ip nat inside source list 1 pool POOL1
   • ip nat pool POOL1 100.0.0.1 100.0.0.1 netmask 255.255.255.0
   • ip nat outside source static 172.16.0.1 100.0.0.1

2. An RFC 1918-addressed PC reaches the public internet through an edge router. There is no translation anywhere on the path and no private tunnel or return route to its subnet. Why will a ping not complete?

   • The ping succeeds because routers forward private addresses by default
   • The ping fails because the private source address is not routable across the public internet
   • The ping succeeds only if OSPF is also configured
   • The ping fails because ICMP is blocked by NAT automatically

3. An engineer configures ip nat pool POOL1 100.0.0.1 100.0.0.2 netmask 255.255.255.0 and ip nat inside source list 1 pool POOL1 for a network with three internal hosts. What happens once all three hosts try to reach the internet at the same time?

   • All three hosts share the two pool addresses using port based translation automatically
   • The third host is unable to get a translation because the pool only has two addresses and dynamic NAT here maps one address per host
   • NAT rejects all three hosts because the pool size does not match the ACL
   • The router automatically expands the pool to accommodate all hosts

4. Which keyword converts a dynamic NAT pool configuration into Port Address Translation (PAT), allowing many inside hosts to share a single public address using different port numbers?

   • overload
   • extended
   • shared
   • multiplex

5. Which command displays the current active NAT translation table on a router?

   • show ip nat translations
   • show ip nat pool
   • show running-config | include nat
   • show ip route nat

6. An engineer runs clear ip nat translation * after testing static and dynamic NAT. Which entries remain in the table afterward?

   • All entries, since the clear command only resets counters
   • Only the dynamic entries, static ones are always removed by this command
   • Only the static entries, since dynamic translations are cleared but static mappings are configured permanently
   • No entries remain, both static and dynamic mappings are removed

7. In NAT terminology, what does the term "inside local" address refer to?

   • The address of an inside host as represented on the inside network, before inside-source translation
   • The public address a host uses when communicating with the outside network
   • The address of an outside host as seen from the inside network
   • The address an outside host is actually configured with

8. A company wants every internal host to share a single public IP address for internet access, since they have far more internal hosts than public addresses available. Which NAT approach best fits this requirement?

   • Static NAT
   • Dynamic NAT without overload
   • PAT (NAT overload)
   • NAT64

9. Which access list is typically referenced by ip nat inside source list <acl> pool <name> to determine which traffic is eligible for dynamic NAT translation?

   • An access list that permits the source subnet of the internal hosts eligible for translation
   • An access list that matches the destination addresses on the internet
   • An access list applied to the outside interface with ip access-group
   • An access list that denies all traffic except ICMP