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src/3-ip-connectivity.md

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+# IP Connectivity
+
+This section covers IP routing concepts, including routing tables, static routing, dynamic routing with OSPFv2, and first-hop redundancy protocols.
+
+## 3.1 Routing Tables
+
+A routing table stores information that routers use to make forwarding decisions. Key components include:
+
+* **Routing Protocol Code:** Indicates the protocol used to learn the route (e.g., O, S, D for OSPF, static, and EIGRP respectively).
+* **Prefix:**  The network address of the destination network.
+* **Network Mask:**  Indicates which bits of the address identify the network and which identify the host.
+* **Next Hop:** The IP address of the next router to which the packet should be forwarded.
+* **Administrative Distance:** A measure of the trustworthiness of a routing source. Lower values are more trusted.
+* **Metric:**  A value used by routing protocols to determine the best path to a destination.
+* **Gateway of Last Resort:** The default route used when no specific route is found for a destination.
+
+## 3.2 Router Forwarding Decisions
+
+Routers use the following criteria to make forwarding decisions:
+
+* **Longest Prefix Match:** The route with the most specific (longest) match to the destination address is preferred.
+* **Administrative Distance:**  If multiple routes with the same prefix length exist, the route with the lower administrative distance is preferred.
+* **Routing Protocol Metric:** If multiple routes have the same prefix length and administrative distance, the route with the lowest metric is preferred.
+
+## 3.3 IPv4 and IPv6 Static Routing
+
+Static routes are manually configured routes. Types of static routes include:
+
+* **Default Route:**  A route that matches any destination and sends traffic to a specified next hop.
+* **Network Route:**  A route to a specific network.
+* **Host Route:** A route to a specific host.
+* **Floating Static Route:** A backup route that is used only if the primary route fails. It has a higher administrative distance than the primary route.
+
+## 3.4 Single Area OSPFv2
+
+OSPF (Open Shortest Path First) is a link-state dynamic routing protocol.
+
+* **Neighbor Adjacencies:** OSPF routers form neighbor relationships with other OSPF routers on the same network.
+* **Point-to-Point:**  OSPF configuration for point-to-point links.
+* **Broadcast:** OSPF configuration for broadcast networks.
+    * **DR (Designated Router):**  Elected on a broadcast network to reduce the number of OSPF adjacencies.
+    * **BDR (Backup Designated Router):**  Takes over if the DR fails.
+* **Router ID:**  A unique identifier for an OSPF router.
+
+## 3.5 First Hop Redundancy Protocols
+
+First Hop Redundancy Protocols (FHRPs) provide gateway redundancy for end devices. They allow multiple routers to share a virtual IP address, and if one router fails, another takes over. Examples include:
+
+* **Hot Standby Router Protocol (HSRP):** Cisco proprietary protocol.
+* **Virtual Router Redundancy Protocol (VRRP):**  An open standard protocol.
+* **Gateway Load Balancing Protocol (GLBP):** Cisco proprietary protocol that allows load sharing between multiple routers.

src/SUMMARY.md

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 - [Chapter 1 Network Fundamentals](1-network-fundamentals.md)
 - [Chapter 2 Network Access](2-network-access.md)
+- [Chapter 3 IP Connectivity](3-ip-connectivity.md)