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Nagios Monitoring: Unknown CPU Stats (CentOS 7)

October 26, 2014 by @HKw@! | No Comments | Filed in centos, Linux, Nagios

Recently i trying to monitor CentOS 7 via Nagios Xi. I noticed that there was Unknown status on the CPU Stats services. It show error message “UNKNOWN: iostat not found or is not executable by the nagios user.”

Unknown iostat

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What is the difference between MBR and GPT?

October 22, 2014 by @HKw@! | No Comments | Filed in Windows

I believe most of the IT folks see this two type of partition table format (MBR and GPT) when you creating new partition. But do your guy really understand what is the difference between this two partition table format?

Here i going to share with you some of the key difference between this two partition table format:-

 Master Boot Record (MBR)

  • A partition supports a maximum of four primary partitions per drive
  • A partition can have maximum of 2 terabytes (TB) (2.19 x 10^12 bytes).

Note: You can use the MBR partition table format for disk drives that never surpass 2 TB in size. This provides you with a bit more space, because GPT requires more disk space than MBR.

GUID Partition Table (GPT)

  • GPT supports a maximum of 128 partitions per drive
  • A partition can have up to 18 exabytes (EB).

Note: If your hard disk is larger than 2 TB, you must use the GPT partition table format. To boot from a GPT partition table, please make sure your BIOS able  support GPT.

Differences Between IPv4 and IPv6

October 18, 2014 by @HKw@! | No Comments | Filed in Networking

Below are the some difference between IPv4 and IPv6:-

IPv4 IPv6
Address Resolution Protocol (ARP) uses broadcast ARP request frames to resolve an IPv4 address to a link-layer address. ARP request frames are replaced with multicast Neighbor Solicitation messages.

Internet Group Management Protocol (IGMP) manages local subnet group membership.

IGMP is replaced with Multicast Listener Discovery messages.

Internet Control Message Protocol (ICMP) Router Discover, which is optional, determines the IPv4 address of the best default gateway.

ICMP Router Discovery is replaced with required ICMPv6 Router Solicitation and Router Advertisement messages.

Uses host (A) resource records in the DNS to map host names to IPv4 addresses.

Uses IPv6 host (AAAA) resource records in DNS to map host names to IPv6 addresses.

Uses pointer (PTR) resource records in the IN-ADDR.ARPA DNS domain to map IPv4 addresses to host names.

Uses pointer (PTR) resource records in the IP6.ARPA DNS domain to map IPv6 addresses to host names.

Must support a 576-byte packet size (possibly fragmented).

Must support a 1280-byte packet size (without fragmentation).