CCNA
Cisco Certified Network Associate certification resources
Introduction to Port Forwarding (and How to Configure It)
Port forwarding maps a specific external port to a specific internal IP address and port, letting external devices reach a service on a private network despite NAT normally blocking any unsolicited inbound connections from ever reaching that internal host. It’s how a home server, a game console, or a remote-access tool becomes reachable from outside...
How to Configure Port Address Translation (PAT)
Port Address Translation (PAT), also called NAT overload, lets many internal devices share a single public address, distinguished from each other by port number rather than needing a separate address for each device. This is the guide that completes our shared NAT lab — if you’ve worked through Static NAT and Dynamic NAT already, PAT...
How to Configure Dynamic NAT
Dynamic NAT automatically maps inside local addresses to a pool of inside global addresses, first-come-first-served — the middle ground between static NAT’s permanent one-to-one mappings and PAT’s many-to-one port sharing approach. It’s the right choice when a known, moderate number of internal devices need outbound internet access, without needing a dedicated public address reserved for...
How to Configure Static NAT on Cisco Routers
Static NAT maps inside and outside addresses one-to-one. It allows external devices to establish a session with internal devices using a statically assigned public address. For example, an internal web server is mapped to a specific inside global address, letting outside clients reach it using a public IP while the server itself keeps its private...
NAT Advantages and Disadvantages
NAT is a genuine trade-off, not a free win. It solved IPv4 exhaustion well enough that IPv6 adoption has taken decades longer than originally expected — but it does that by breaking assumptions a lot of other protocols were originally built on. Understanding both sides matters for CCNA and CCNP exams specifically, since questions routinely...
What Are the Types of NAT Translation?
There are three types of NAT: static NAT, dynamic NAT, and Port Address Translation (PAT), also called NAT overload. They all solve the same underlying problem — mapping private addresses to public ones — but they differ significantly in how permanent the mapping is and how many public addresses they actually require to function. This...
NAT Terminology Explained: CCNA 200-301 Must-Know Address Types
As discussed before, NAT translates private IP addresses into public IP addresses. In the process of translation, there are different operations involved, and understanding each of them requires understanding NAT terminology. Before understanding NAT in detail, it is important to understand the four NAT address types — inside local, inside global, outside local, and outside...
Network Address Translation (NAT) & RFC 1918 Private IPv4 Addresses
IPv4 only has about 4.3 billion addresses total — a number that looked enormous in the early 1980s and nowhere near enough once personal computing and the web took off. Network Address Translation, alongside RFC 1918 private addressing, is the pairing that kept IPv4 usable for decades past when it otherwise would have run out....
Configuring a Stateful DHCPv6 Server on a Cisco Router
Stateful DHCPv6 is the IPv6 mode that behaves the way DHCPv4 always has: the server assigns the address itself, tracks which client has which address, and hands out supplementary options alongside it — no SLAAC involved on the client side at any point. That’s the core distinction from stateless DHCPv6, and it changes almost every...
Configuring a Stateless DHCPv6 Server on a Cisco Router
Stateless DHCPv6 does one job and one job only: it hands out supplementary configuration — DNS servers, a domain name — to clients that have already generated their own IPv6 address through SLAAC entirely on their own. It never assigns an address itself, under any circumstances. That distinction shapes every command in this setup, and...