Table of contents
1. How does the switch forward packets?
4. Please calculate the available IP address range of this subnet 192.168.100.5/17
5. How to release DHCP under WINDOWS, and then obtain IP address again?
6. How many packages does OSPF have, and what is the function of each package?
7. What are the neighbor states of OSPF?
8. The solution to BGP split horizon
9. How to solve BGP routing black hole
10. What are the LSAs in OSPF and what are the special areas?
▲▲▲Need more network worker interview questions▲▲▲
Don't forget to follow + like
1. How does the switch forward packets?
The switch forwards data according to the MAC address table. The specific principles are as follows:
Learning based on source MAC address
Forwarding based on destination MAC address
If a broadcast frame or an unknown unicast frame is received, all ports except the source port in this VLAN are forwarded.
A MAC address is learned by multiple interfaces, choose the latest one (like the new and dislike the old)
2. If a data packet is forwarded by a Layer 2 switch, will the source MAC of the data packet change? If it is forwarded by a layer-3 switch, what will the source MAC become?
After being forwarded by a Layer 2 switch, the source MAC address of the data packet will not change
After being forwarded by a Layer 3 switch, the source MAC address of the data packet will change to become the MAC address of the outgoing interface of the Layer 3 switch.
3. How to view the ARP table of the PC, how to clear the ARP table, and how to manually add static ARP entries?
ARP -a
ARP -d
ARP -S ip address MAC address
4. Please calculate the available IP address range of this subnet 192.168.100.5/17
192.168. 100.5 ------into binary
192.168.01100100.5
Network address: the network bit remains unchanged, the host bit is all 0 ---192.168.0.0
Broadcast address: the network bit is not enough, the host bit is all 1---192.168.01111111.11111111-192.168.127.255
IP address range: 192.168.0.1 to 192.168.127.154
| 27 |
26 |
25 |
24 |
23 |
22 |
21 |
20 |
| 128 |
64 |
32 |
16 |
8 |
4 |
2 |
1 |
5. How to release DHCP under WINDOWS, and then obtain IP address again?
C:\Users\joinlabs>ipconfig /release release DHCP
C:\Users\joinlabs>ipconfig /renew to obtain the IP address again
6. How many packages does OSPF have, and what is the function of each package?
HELLO: Establish and maintain neighbor relationships
DBD Database Description: Summary information for the link state database
LSR Link State Request
LSU Link Status Update
LSACK Link Status Acknowledgment
7. What are the neighbor states of OSPF?
DOWN There is a problem with running OSPF/OSPF just now
INIT initialization received the other party's HELLO packet
TWO-WAY received the other party's HELLO packet, and saw its own router-id, choose DR and BDR?
EXSTART pre-start, select the master/slave whose router-id is greater and whoever is the master
EXCHANGE exchange mutual exchange DBD
LOADING send LSR LSU LSACK
FULL adjacency
8. The solution to BGP split horizon
- Fully connected
- route reflector
- federal
9. How to solve BGP routing black hole
- Import BGP routes into IGP
- Fully connected
- MPLS
The above three methods, the optimal solution is MPLS,
10. What are the LSAs in OSPF and what are the special areas?
| LSA type |
Effect of LSA |
| Router |
Generated by each device, describes the link status and cost of the device, and propagates in the area to which it belongs. |
| Network |
Generated by DR (Designated Router), it describes the link status of the network segment and propagates in the area to which it belongs. |
| Network-summary |
Generated by ABR, describes the route of a certain network segment in the area, and advertises it to other areas |
| ASBR-summary |
Generated by the ABR, describes the route to the ASBR, and advertises it to other related areas except the area where the ASBR is located. |
| AS-external |
Generated by ASBR, describes the route to the outside of the AS, and advertises to all areas |
| NSSA |
Generated by the ASBR, it describes the route to the outside of the AS and is only propagated in the NSSA area. |
| area type |
effect |
| backbone area |
The backbone area is the central area connecting all other OSPF areas, usually represented by area 0 |
| standard area |
Standard area is the most general area, it carries intra-area, inter-area routing, and external routing |
| stub area |
Reject Type 4 and Type 5 LSAs Automatically deliver a default route with a Type 3 LSA |
| Totally STUB area |
Reject Type 3, 4, and 5 LSAs Automatically deliver a default route with a Type 3 LSA |
| NSSA |
Reject Type 4 and Type 5 LSAs and introduce Type 7 LSAs Automatically deliver a default route of a Type 7 LSA |
| Totally NSSA |
Reject Type 3, 4, and 5 LSAs, and introduce Type 7 LSAs Automatically deliver a default route of type 3 and type 7 LSA |
▲▲▲Need more network worker interview questions▲▲▲
Don't forget to follow + like