Windows route table Basics

Route table items

IPv4 Route Table===========================================================================Active Routes:Network Destination        Netmask          Gateway       Interface  Metric          0.0.0.0          0.0.0.0        10.12.0.1      10.12.32.47     20        10.12.0.0    255.255.192.0         On-link       10.12.32.47    276      10.12.32.47  255.255.255.255         On-link       10.12.32.47    276     10.12.63.255  255.255.255.255         On-link       10.12.32.47    276        127.0.0.0        255.0.0.0         On-link         127.0.0.1    306        127.0.0.1  255.255.255.255         On-link         127.0.0.1    306  127.255.255.255  255.255.255.255         On-link         127.0.0.1    306     192.168.56.0    255.255.255.0         On-link      192.168.56.1    276     192.168.56.1  255.255.255.255         On-link      192.168.56.1    276   192.168.56.255  255.255.255.255         On-link      192.168.56.1    276        224.0.0.0        240.0.0.0         On-link         127.0.0.1    306        224.0.0.0        240.0.0.0         On-link      192.168.56.1    276        224.0.0.0        240.0.0.0         On-link       10.12.32.47    276  255.255.255.255  255.255.255.255         On-link         127.0.0.1    306  255.255.255.255  255.255.255.255         On-link      192.168.56.1    276  255.255.255.255  255.255.255.255         On-link       10.12.32.47    276===========================================================================Persistent Routes:  None

Ping two types of errors: not reachable, request timeout;

1. The path is not reachable. Search all entries and no matching network is found.

For example, delete the default gateway.

route delete 0.0.0.0

Ping Output Error of 1.2.3.4 again

2. The request times out and finds the matching entry. However, after an ICMP packet is sent to the matching entry, no response is received at the specified time.

For example, add a default gateway

route add 0.0.0.0 mask 0.0.0.0 10.12.0.1

Ping 1.2.3.4 and the output times out.

Route Selection

When TCP/IP needs to initiate a communication to an IP address, it evaluates the route table to determine how to send packets.

The evaluation process is as follows:

(1) TCP/IP uses the destination IP address to communicate with and the network mask of each route entry in the routing table for phase and calculation. If the phase and result match the network address of the corresponding route entry, this route entry is recorded.

(2) After all route entries in the route table are calculated, the longest matching route entry in the route entry under the TCP/IP Selection Record (the network mask contains a route entry with a maximum of "1) to communicate with the destination IP address.

(3) If there are multiple longest matching routes, select a route entry with the lowest number of hops.

(4) If there are multiple longest matching routes with the lowest hops, then:

(4.1) If a response packet is sent and the source IP address of the packet is the IP address of an interface with the longest matching route, select the longest matching route.

(4.2) in other cases, the binding priority of the network interface corresponding to the longest matching route is determined in the advanced settings of the network connection.

Bridged networking topology

Nat Topology

Host-only Topology

Refer:

1. Understand the route table and default gateway in Windows

2 virtual box Virtual Network Mode

3 Broadcast Data Transmission