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BeginnerPublished 2026-07-02

Inside, Outside & the Translation Table

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Configure static one-to-one NAT for two inside hosts on R1, mark inside/outside interfaces correctly, and read the four-column NAT translation table (inside local/global, outside local/global). Verify from both sides and relate observed traffic to table entries.

Track
Est. time
40 minutes
Difficulty
Beginner
Topics

Learning objectives

  • Identify and mark NAT inside vs. outside interfaces on an IOS edge router
  • Configure two static one-to-one NAT translations for specific inside hosts
  • Interpret all four NAT table columns: inside local/global and outside local/global
  • Validate successful translation and return traffic using host pings and router show commands
  • Relate NAT statistics and translations to real flows to and from the ISP segment

Troubleshooting focus

  • Interfaces not marked with ip nat inside/outside (no translations appear)
  • Wrong public addresses (not on the outside /29) cause return traffic to fail
  • Missing default route on R1 prevents outbound reachability even if NAT is correct

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How this lab is graded
  • Build it your way. Where a lab lets you choose a value — a VLAN name, an interface description — grading checks that you configured it, not which name you picked. Names that another line has to reference, like an ACL applied with access-class, are stated in the guide and do have to match.
  • Addresses, modes and protocol keywords are exact. An IP address, a subnet mask, switchport mode trunk, an encapsulation — these carry the meaning of the lab, so they are graded as written in the guide.
  • Grading reads your saved configuration. Export the lab from CML after you have configured it, and make sure anything you set is in the running-config — a change that only exists in a terminal session never reaches the grader.
  • You can submit as many times as you like. Your best score stands, and each attempt tells you which checks passed so you can work the gaps.
  • Scored something you believe is correct? Use Report an issue on this page — that is exactly how the grading fixes in the changelog got found.

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