As long as it is an interview, it is necessary to bring subjective emotions, and how to guide the chemistry with the interviewer is not xiao Pang’s strong point.
As far as I am concerned, I pay more attention to the way of answering questions than the superficial right and wrong. Just like answers on Zhihu, only 80 points can be given for step-by-step answers. It is the embodiment of personal added value to further clarify principles and bring new ideas through questions.
How to absorb the knowledge of others, its own system, rather than simply take doctrine. This is a lesson for you.
The OSI model
Questions about the OSI model?
In the OSI model, what layer does a protocol belong to and by what criteria?
In the OSI seven-tier model, who generates and unpacks packets at each tier?
switches
When the switch port is set to VLAN Trunk mode, what information is inserted in the packet forwarding?
Why does a switch need an IP?
Access to a 100Mbps network cable, after the switch, will encounter a bottleneck?
What does the switch do after receiving a frame?
During VLAN learning, do untagged frames go out of the VLAN switch?
How can VLANS on the same switch be isolated? What does convergence mean in the generative tree protocol?
How to understand STP?
How to remember network engineering techniques, such as STP, HSRP, etc.?
The historical background of STP to RSTP?
CISCO PortFst port concept? Beg superior person to explain!
What kind of network needs MSTP?
Why cannot the IP addresses in the address pools of the active and standby switches in the DHCP + VRRP group conflict? But DHCP has its own mechanism to prevent address collisions! ?
Why does a network cable short circuit cause a broadcast storm?
How to better understand the difference between broadcast routing and link layer broadcast?
What is the relationship between the MAC address of the operating system and that of the physical nic on a host in the LAN?
What are the differences and relationships between IP addresses and MAC addresses?
Why can I see another host only after ping through ARP broadcast on a LAN?
When the number of clients on the LAN exceeds 254, how can I resolve the problem that the DHCP address pool is insufficient?
Why cannot Ethernet receive packets larger than 1500 bytes?
Routing technology
How can I defend against attacks between multiple routers?
What’s the difference between host routing, network routing, and default routing?
Can IP networks be like road traffic networks, where each packet decides its own forwarding path?
A bridge works at the data link layer and is a Layer 2 device, but it can connect lans of different network segments. It is equivalent to a Layer 3 switch.
Why network devices (switches and routers) use RJ45 ports as console ports but do not support TCPIP and can only use COM for communication?
What is the significance of a router’s maximum number of concurrent connections and the number of new connections per second?
Why use 100M wired port for 300M wireless routing?
[See schematic diagram] The two routers separated by the light cat have several devices under each router. Can they communicate with each other?
Class routing classification problem?
Do two hosts on the same network segment need a router to communicate?
How do computers in subnets in different network segments find each other’s subnet IP addresses?
How does the network layer process the destination IP address of an IP packet is a private IP address?
How do two computers transmit data to each other through network cables?
Where is the IP fragment reassembled?
About IPv4 sharding and CSMA/CD /CA?
What exactly is IPOE?
Why use a MAC address when you have an IP address?
Why does the MTU setting of the router affect wechat picture sending?
When the subnet mask is 255.255.255.255?
What are the specific meanings and essential differences between point to point communication and end to end communication in computer networks?
What’s the difference between dial-up and broadband?
A bunch of questions about bandwidth, network transmission rates?
Why in WAN communication, the longer the physical distance, the worse the communication quality of the channel? More congestion and delays?
Routing protocol
What are the differences between SRTT and RTO definitions in the EIGRP neighbor table?
EIGRP network command?
BGP Next Hop attribute problem?
Does the BGP routing table record the entire routing path?
Is BGP configuration incorrect?
Why does OSPF divide network types?
Rip and OSPF are application-layer protocols, but routers only work at the network layer, data link layer, and physical layer.
Is OSPF used on a LAN or a WIDE area network?
If the router runs OSPF, does the keepalive configuration of the port affect the default cost?
Who can elaborate on which layer RIP protocol belongs to OSI7 layer reference protocol?
What is an Autonomous System Number, and how does it work?
Why is R3 ABR over ASBR?
Network protocol
Are all network requests based on TCP/IP?
What application layer protocols are still active?
Which is more bandwidth-efficient, UDP broadcast or TCP connection?
How to understand TCP connection-oriented and UDP connectionless (not connection-oriented)?
Why do you need UDP when IP can also be used for connectionless and unreliable data transfer?
Which headers of TCP/IP packets remain unchanged during transmission over the Internet?
What exactly does TCP reliability mean?
Why is TCP a three-way handshake, why not two or four?
How to explain the differences between TCP/UDP and HTTP, FTP, SMTP and other application-layer protocols in a simple way?
What is the relationship between sliding window size in TCP flow control, 16-bit window size in TCP field, MTU, MSS, cache size?
In TCP/IP stack, why IP layer is responsible for sharding?
How does TCP maintain long connections and recognize different requests?
TCP fast retransmission is a triple redundant ACK.
In TCP/IP, is the ISN serial number assigned when a connection is established?
In the four TCP breakups, how did the passive closing party know that the data had been received?
In Tcp/IP, before one end sends data to the other end, do THE ARP request and reply or establish a Tcp connection first?
TCP/IP: Is ARP used to transmit data over a wide area network?
MSS in TCP is 536, right?
How to negotiate TCP load?
Can TCP interrupts be waved 3 times?
In TCP programming, what are the criteria for a successful connect?
Why send FIN+ACK instead of FIN on the first wave?
TCP sliding window send window and receive window is correct?
TCP has a congestion control policy. Why does the network crash?
Why aren’t HTTP downloads downloaded directly but rather speeded up bit by bit? What will happen if you download it directly?
If the data link layer has verification, why does the network layer need verification and the transport layer need verification?
What exactly does TCP port refer to? Why does it have a port? How do you understand it?
What is the nature of establishing connections in network communication?
NAT
How does NAT work?
How does UNDERSTANDING NAT complicate Ipsec?
If VMS use NAT to connect to the network, does the data traffic carry information about dedicated servers?
MPLS VPN
How can a carrier network carry different traffic?
The MPLS PHP?
How to understand the relationship between VPN instances and VRFS on MPLS VPN networks?
IPSec VPN
What are the advantages of IKEv2 over other VPN protocols?
How to explain the connection and difference between PPTP and L2TP in VPN in common language?
Why do some carriers use L2TP/PPTP dial-up mode? What are the differences between these two modes and PPPOE?
multicast
About the registration message in the multicast protocol PIM SM! ?
Whose IP address is the multicast IP address?
What is the significance of binding class D addresses to multicast MAC addresses?
Trouble shooting
Can traceroute ensure that each group uses the same routing path?
How do you encounter LAN IP addresses on the Internet?
What about frequent packet loss and delay when using a router to surf the Internet?
Why is the TTL value incorrect when the aliyun server ping?
The proxy server is used to access the Internet on the Intranet, but the Terminal ping fails. Why is that?
What are the practical implications of banning ping and tracert in the enterprise?
Program ape and big god are good, ask a question about server network, a layman has caught blind T T for three days, thank you! ?
Every time after the power failure, PPPoE automatic connection to connect for a long time, what is the principle?
The network lost a packet. Where did the packet go?
Network security
Which RSA public key is used for encryption and which is used for decryption?
Zero foundation, want to be a network security engineer, where CAN I learn, or have any suggestions, thank you?
How does SSL/TLS access block work?
The data center
What is the architecture of the data center network of Alibaba, Baidu and other Domestic Internet companies? There is an in-house RESEARCH and development team for this no, what are the priorities?
Why do VMS in cloud computing/data centers need to be migrated on the same VLAN?
What are the downsides of flattening data center network architectures to two tiers?
How attractive is VXLAN?
other
What is the network structure inside the campus of general colleges and universities?
How to become a Network architect?