Technological – Page 4

October 14, 2016Networking, Unix Technologies

Setup and Test Bind DNS Zone File Replication to Slave Servers on CentOS

Scenario: You are on-boarding/bringing up a new Bind DNS server (say NSHost3 – 198.164.12.103) to replace/upgrade your existing Bind DNS server (NSHost2 – 198.164.12.102) You have installed Bind 9.8 as shown on the new server [root@NSHost3 ~]# named -vBIND 9.8.2rc1-RedHat-9.8.2-0.47.rc1.el6_8.1[root@NSHost3 ~]# You want to configure NSHost3 as slave server for some of the zones are primarily hosted on NSHost1 (198.164.12.101) in your other Data centre You are NOT running or have allowed the tcp/udp port#53 in your iptables Firewall on both NSHost1 and NSHost3 servers Implementation: Configuring your new server NSHost3 as slave to NSHost1 server requires updating named.conf […]

September 26, 2016Citrix, Networking, Unix Technologies

FIX: CentOS 6.8 Minimal Install: Device eth0 does not seem to be present, delaying initialization

Scenario: You are running your CentOS virtual machine on XenServer with a Static IPv4 IP-Address. All of sudden your CentOS system loses network connectivity. Upon checking you notice that none of the Network adapters are detected. The IP-address assigned gets allocated to other systems on the network. Upon attempting to run command ‘service network restart’, you encounter error message: Bringing up interface eth0: Device eth0 does not seem to be present, delaying initialization. [FAILED] You notice that Same error persists even when you add more NICs to the system Same error persists even when you remove or manually update MAC […]

July 25, 2016July 25, 2016VMware

VMWare Internals: Understanding how vMotion works

Understanding how vMotion works This is my first article on detailing VMWare Internals and in this article we discuss about how VMWare vMotion works and what happens in the background during the vMotion. About vMotion vMotion is one of the key feature of VMWare technology. vMotion is a live migration/movement of running Virtual Machines (VMs) between physical hosts with ZERO downtime and offering continuous service availability. It is transparent to the VM Guest OS & applications as well as to the end user. The primary use case is to support manual load balancing of your ESX servers in cases like, […]