Google Interview Hacks

What does Latency mean? Latency is a networking term to describe the total time it takes a data packet to travel from one node to another. In other contexts, when a data packet is transmitted and returned back to its source, the total time for the round trip is known as latency. Latency refers to time interval or delay when a system component is waiting for another system component to do something. This duration of time is called latency.

What does Proxy Server mean? A proxy server verifies and forwards incoming client requests to other servers for further communication. A proxy server is located between a client and a server where it acts as an intermediary between the two, such as a Web browser and a Web server. The proxy server's most important role is providing security.

What is a ping? Ping is a network diagnostic tool used primarily to test the connectivity between two nodes or devices. To ping a destination node, an Internet Control Message Protocol (ICMP) echo request packet is sent to that node. If a connection is available, the destination node responds with an echo reply. Ping calculates the round-trip time of the data packet's route from its source to the destination and back, and determines whether any packets were lost during the trip.

What is Wireshark? Wireshark is a free and open-source packet analyzer. It is used for network troubleshooting, analysis, software and communications protocol development, and education.

What are the HTTP methods? GET, HEAD, POST, PUT, DELETE, CONNECT, OPTIONS, TRACE These method names are case sensitive and they must be used in uppercase.

What are the 6 TCP flags? (Mnemonic) Unskilled Attackers Pester Real Security Folks Unskilled = URG Attackers = ACK Pester = PSH Real = RST Security = SYN Folks = FIN

What are parts of the IP header in an e-mail? Version, IHL, DSCP, ECN, Total Length, Identification, Flags, Fragment Offset, Time to Live, Protocol, Header Checksum, Source Address, Destination Address, and Options.

What is a WHOIS search? A WHOIS search will provide information regarding a domain name, such as example.com. It may include information, such as domain ownership, where and when registered, expiration date, and the nameservers assigned to the domain.

What is ifconfig? ifconfig is a system administration utility in Unix-like operating systems for network interface configuration. The utility is a command line interface tool and is also used in the system startup scripts of many operating systems. It has features for configuring, controlling, and querying TCP/IP network interface parameters. Ifconfig originally appeared in 4.2BSD as part of the BSD TCP/IP suite.

What is Dig? Dig (domain information groper) is a network administration command-line tool for querying Domain Name System (DNS) name servers. Dig is useful for network troubleshooting and for educational purposes. It can operate in interactive command line mode or in batch mode by reading requests from an operating system file.

What does Cross-Site Request Forgery (CSRF) mean? Cross-site request forgery (CSRF) is a type of website exploit carried out by issuing unauthorized commands from a trusted website user. CSRF exploits a website's trust for a particular user's browser, as opposed to cross-site scripting, which exploits the user's trust for a website. This term is also known as session riding or a one-click attack.

What is Cross Site Scripting (XSS)? Cross Site Scripting (XSS) is the process of addition of malicious code to a genuine website to gather user's information with a malicious intent. XSS attacks are possible through security vulnerabilities found in Web applications and are commonly exploited by injecting a client-side script. Although JavaScript is usually employed, some attackers also use VBScript, ActiveX or Flash.

What is the NIC and on what layer(s) does it reside? The network interface controller (NIC) implements the electronic circuitry required to communicate using a specific physical layer and data link layer standard such as Ethernet, Fiber Channel, Wi-Fi or Token Ring. This provides a base for a full network protocol stack, allowing communication among small groups of computers on the same LAN and large-scale network communications through routable protocols, such as IP. The NIC allows computers to communicate over a computer network, either by using cables or wirelessly. The NIC is both a physical layer and data link layer device.

What are the subnet masks for ITv4 network in dotted decimal for A, B, and C? A= 255.0.0.0 B=255.255.0.0 C=255.255.255.0

What is a MAC address? A media access control address (MAC address) is a unique identifier for an Ethernet or network adapter over a network. It distinguishes different network interfaces and is used for a number of network technologies, particularly most IEEE 802 networks, including Ethernet. In the OSI model, MAC addresses occur in the Media Access Control Protocol sub-layer. A MAC address is also known as physical address, hardware address and burned-in address.

What is ARP poisoning? Address Resolution Protocol poisoning (ARP poisoning) is a form of attack in which an attacker changes the Media Access Control (MAC) address and attacks an Ethernet LAN by changing the target computer's ARP cache with a forged ARP request and reply packets. This modifies the layer -Ethernet MAC address into the hacker's known MAC address to monitor it. Because the ARP replies are forged, the target computer unintentionally sends the frames to the hacker's computer first instead of sending it to the original destination. As a result, both the user's data and privacy are compromised. An effective ARP poisoning attempt is undetectable to the user.

What is ARP? Address Resolution Protocol (ARP) is a low-level network protocol for translating network layer addresses into link layer addresses. ARP lies between layers 2 and 3 of the OSI model, although ARP was not included in the OSI framework and allows computers to introduce each other across a network prior to communication. Because protocols are basic network communication units, address resolution is dependent on protocols such as ARP, which is the only reliable method of handling required tasks.

What Is a Trojan horse? The Trojan Horse will appear to be useful software but will do damage once installed or run on the computer. Those on the receiving end of a Trojan Horse are usually tricked into opening them because they appear to be receiving legitimate software or files from a legitimate source and results vary. Some Trojans are designed to be more annoying than malicious or they can cause serious damage by deleting files and destroying information on the system. Trojans can create a backdoor on the computer that gives malicious users access to your system, possibly allowing confidential or personal information to be compromised.

What Is a Worm? A worm is similar to a virus by design and is considered to be a sub-class of a virus. It self-replicates and travels unaided, often sending massive quantities of itself out often through infiltration of an e-ail address book. Due to the copying nature of a worm and its capability to travel across networks the end result in most cases is that the worm consumes too much system memory (or network bandwidth), causing Web servers, network servers and individual computers to stop responding.

What is a virus? A computer virus attaches itself to a program or file enabling it to spread from one computer to another, leaving infections as it travels. Like a human virus, a computer virus can range in severity: some may cause only mildly annoying effects while others can damage your hardware, software or files. Almost all viruses are attached to an executable file, which means the virus may exist on your computer but it actually cannot infect your computer unless you run or open the malicious program.