Linux systems administrator ii Interview Questions
21
Linux Systems Administrator Ii interview questions shared by candidates
When does DNS use TCP instead of UDP
4 Answers↳
DNS use TCP for zone transfer.
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Maximum UDP packet size is 512 bytes (or 4096, with the extension of DNS protocol). When the request is larger then a max. UDP size, DNS will switch to TCP. Less
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speed
User has lost root password, how do you reset?
4 Answers↳
Boot in single mode by typing E on the selected the kernel in grub then add S or single or 1 to the end of line eg. then B to boot the selected kernel. once in the single-user mode disable SElinux with below command eg: setenforce 0 now using passwd command "With SElinux Off as Selinux will not let you change it" eg: [root@centos images]# passwd Changing password for user root. New password: your-password BAD PASSWORD: it is based on a dictionary word BAD PASSWORD: is too simple Retype new password: your-password passwd: all authentication tokens updated successfully. Less
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Actually the easiest way to do this is to single the box in run-level 1 then use the standard passwd tools to update the hash. That's far simpler than using a live cd and editing the shadow file. This a network based kvm. is an operation that can be done at the DC or over ipmi or Less
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init 1, change root password... I missed this one.
Define the difference between a hub and a switch
3 Answers↳
A hub works on the physical layer (layer 1) and doesn't separate collision or broadcast domains. A switch works on the data link layer (layer 2) and separates collision domains. This allows multiple devices to talk at full duplex using one switch. A router works on the network layer (layer 3) and separates both collision domains and broadcast domains. Less
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A hub works on the physical layer, where as the switch works on the datalink layer . A Switch creates a broadcast domain for each port and allows for full duplex of data allowing you to TX and RX at the same time. A hub is a shared device, it will propagate broadcast traffic. Most are only half duplex . Less
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Network topology. haven't used since collage. Googled and found hub propogates to many servers at once (Token Ring) and Switch uses propogation to different subnets. Less
Provide the IP address of a host that's pinging you.
2 Answers↳
netstat installation didn't have ICMP support. Use tcpdump.
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tcpdump.....
If you had a problem with another employee, how would you deal with it?
1 Answers↳
I would talk to that employee privately, brief him my pro's and con's related to the topic(issue) and get his concerns politely and try to resolve the issue with him, if id not get resolved nicely then I would prefer to have him with my supervisor and let him resolve Less