The default subnet mask for class A addresses is ______.

There are two hops from the source device to the destination device. Use the tracert command to detect the path. When the first hop is detected, the source device sends a UDP packet with a TTL of 1 to a larger port of the destination device. When the packet reaches the middle hop, the TTL will change to 0, so the device responds to the source device. Respond to an ICMP______ message.

Both VLAN technology and port isolation technology can achieve Layer 2 isolation of data.

Three MSR routers are connected in the same LAN network, as shown in the figure. Run OSPF on the LAN interconnection network segment of the three routers, and the DR priorities of RTA, RTB, and RTC are 2, 2, and 3 respectively.

Due to the failure of the RTC LAN link, only RTA and RTB are currently working normally, and the OSPF neighbor status between RTA and RTB is stable. So _____ . (Multiple choice)

The following routing information is seen on the MSR router running RIP:
<MSR>display ip routing-table 6.6.6.6
Routing Table: Public
Summary Count: 2
Destination/Mask Proto Pre Cost NextHop Interface
6.6.0/24 RIP 100 1 100.1.1.1 GE0/0
6.0.0.0/8 Static 60 0 100.1.1.1 GE0/0
At this time, the router receives a data packet with a destination address of 6.6.6.6, then ______.