Domain 4 Review: IP Services

0s13★ 30 XP

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Domain 4 Review: IP Services

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Lesson format8 sections2 practice itemsUpdated Oct 2, 2026

Domain 4 is only 10% of the exam but covers a lot of ground: DHCP, DNS, NAT, NTP, SNMP, syslog, and QoS basics. Don't over-invest here. Focus on the high-yield items — NAT configuration and troubleshooting, DHCP relay, and NTP — and treat the rest as concepts you should recognize, not configure from memory.

#High-Yield Topics#link

▪DHCP DORA process — DISCOVER, OFFER, REQUEST, ACK
▪DHCP relay — `ip helper-address` on the client-facing interface
▪DHCP options — gateway (`default-router`), DNS (`dns-server`), lease time
▪NAT inside/outside interfaces — must be marked or NAT doesn't work
▪Static NAT — one-to-one, for servers
▪Dynamic NAT — pool-based, one-to-one from a pool
▪PAT (NAT overload) — many-to-one with port differentiation
▪NAT ACL — selects which traffic gets translated
▪NTP stratum — lower is better; stratum 16 = unsynchronized
▪Syslog severities — 0 (emergency) to 7 (debugging)
▪SNMP — v2c uses community strings, v3 uses user-based auth+priv

#NAT Configuration Checklist#link

Mark inside and outside interfaces (`ip nat inside`, `ip nat outside`)
Define an ACL matching inside traffic to be translated
Configure `ip nat inside source list X interface Y overload` for PAT
Or configure static NAT for servers: `ip nat inside source static 10.10.10.50 203.0.113.50`
Verify with `show ip nat translations` and `show ip nat statistics`

★ 15 XPeasy

exercise BLOCK (★ 15 XP)

What does `ip helper-address 10.10.99.10` on a router interface do?

Select your proof vectors above

★ 15 XPmedium

exercise BLOCK (★ 15 XP)

In a NAT configuration, what happens if you forget to mark interfaces with `ip nat inside` and `ip nat outside`?

Select your proof vectors above

callout

Domain 4 is 10% of the exam. NAT and DHCP relay are the highest-yield items. If you understand those two deeply and can recognize the others, you'll do fine on this domain. Section 21 continues with security fundamentals review.

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High-Yield Topics NAT Configuration Checklist

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October 2, 2026

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{
  "mcpServers": {
    "vulnarex": {
      "command": "npx",
      "args": ["-y", "@modelcontextprotocol/server-fetch"],
      "env": { "MCP_FETCH_URL": "https://vulnarex.com" }
    }
  }
}

MCP Server Card/.well-known/mcp.json A2A Agent Card/.well-known/agent-card.json API Catalog/.well-known/api-catalog robots.txt/robots.txt

Laboratory sanity code

Isolate active probes on matched virtual networks and keep execution streams sandboxed.

#High-Yield Topics#link

▪DHCP DORA process — DISCOVER, OFFER, REQUEST, ACK
▪DHCP relay — `ip helper-address` on the client-facing interface
▪DHCP options — gateway (`default-router`), DNS (`dns-server`), lease time
▪NAT inside/outside interfaces — must be marked or NAT doesn't work
▪Static NAT — one-to-one, for servers
▪Dynamic NAT — pool-based, one-to-one from a pool
▪PAT (NAT overload) — many-to-one with port differentiation
▪NAT ACL — selects which traffic gets translated
▪NTP stratum — lower is better; stratum 16 = unsynchronized
▪Syslog severities — 0 (emergency) to 7 (debugging)
▪SNMP — v2c uses community strings, v3 uses user-based auth+priv

#NAT Configuration Checklist#link

Mark inside and outside interfaces (`ip nat inside`, `ip nat outside`)
Define an ACL matching inside traffic to be translated
Configure `ip nat inside source list X interface Y overload` for PAT
Or configure static NAT for servers: `ip nat inside source static 10.10.10.50 203.0.113.50`
Verify with `show ip nat translations` and `show ip nat statistics`

★ 15 XPeasy

exercise BLOCK (★ 15 XP)

What does `ip helper-address 10.10.99.10` on a router interface do?

Select your proof vectors above

★ 15 XPmedium

exercise BLOCK (★ 15 XP)

In a NAT configuration, what happens if you forget to mark interfaces with `ip nat inside` and `ip nat outside`?

Select your proof vectors above

callout