[{"content":" IPv6 Packet Header Structure An IPv6 (Internet Protocol version 6) packet consists of a fixed-length 40-byte basic header, followed by optional extension headers and the payload. Compared to the IPv4 header, the number of fields is reduced, and optional information is separated out into extension headers. This article explains the role of each field in the basic header.\nDescription of Each Field Field Name Size Description Version 4 bits Indicates the IP version. Fixed at 6 for IPv6. Traffic Class 8 bits Equivalent to IPv4\u0026rsquo;s Type of Service field. Represents packet priority and congestion notification, used as DSCP and ECN. Flow Label 20 bits A value used to identify packets belonging to the same flow (a sequence of related communication). Set randomly by the sender; routers can use this value for priority control and load balancing without re-classifying the packet. Payload Length 16 bits The number of bytes of extension headers plus data, excluding the basic header. Does not include the 40 bytes of the basic header itself. Next Header 8 bits Equivalent to IPv4\u0026rsquo;s Protocol field. Indicates the type of the header that immediately follows — the type of the next extension header if one follows, or the upper-layer protocol type (TCP, UDP, etc.) otherwise. Hop Limit 8 bits Equivalent to IPv4\u0026rsquo;s TTL. The maximum number of router hops the packet may traverse; decremented by 1 at each router and discarded once it reaches 0. Source Address 128 bits The source IPv6 address of the packet. Destination Address 128 bits The destination IPv6 address of the packet. Key Differences from the IPv4 Header The following fields present in the IPv4 header have been removed or changed in the IPv6 basic header.\nHandling in IPv4 Handling in IPv6 Header Checksum Removed. Error detection is handled by the upper layer (TCP/UDP) or lower layer (Ethernet, etc.), reducing recalculation cost at the IP level. Identification, Flags, Fragment Offset Removed from the basic header. When fragmentation is needed, it is added as a Fragment extension header. Fragmentation along the path by routers no longer occurs — only the source performs it. IHL (Header Length) Removed. Unnecessary since the basic header is always a fixed 40 bytes. Options Removed. Replaced by a scheme in which Extension Headers are chained together via the Next Header field. Common Extension Header Values The value of the Next Header field indicates the type of extension header or upper-layer protocol. Common values are as follows.\nNext Header Value Type 0 Hop-by-Hop Options extension header 6 TCP 17 UDP 43 Routing extension header 44 Fragment extension header 50 ESP (IPsec) 51 AH (IPsec) 58 ICMPv6 59 No Next Header (indicates no header follows) 60 Destination Options extension header Extension headers are chained together using the Next Header field, eventually reaching the upper-layer protocol. Protocol numbers (Next Header values) are managed by IANA, and the full list of assigned values is published here.\nIANA - Protocol Numbers Header Size Note that while IPv4\u0026rsquo;s Total Length represents the length of the entire packet including the IP header, IPv6\u0026rsquo;s Payload Length does not include the 40-byte basic header. Item Size Notes IPv6 basic header Fixed at 40 bytes A simplified field layout that is always a fixed length. Extension headers Variable length (zero or more) Chained together, with each one\u0026rsquo;s type indicated by the Next Header field. Entire IPv6 packet Up to 65535 bytes (excluding jumbograms) The 40-byte basic header plus the length indicated by Payload Length. Unlike IPv4, if the packet size is larger than the MTU of a link along the path, routers do not perform fragmentation. The source host determines the appropriate size via Path MTU Discovery and, if necessary, fragments the packet itself using a Fragment extension header. A router that receives a packet exceeding the MTU discards it and returns an ICMPv6 Packet Too Big message to the source.\nRelated RFCs RFC Title Summary RFC 8200 Internet Protocol, Version 6 (IPv6) Specification The current IPv6 specification. Defines the basic header structure and the extension-header chaining scheme. An Internet Standard that replaced RFC 2460. RFC 2460 Internet Protocol, Version 6 (IPv6) Specification The previous IPv6 specification. Obsoleted by RFC 8200, but often referenced for historical context. ","date":"1 August 2026","externalUrl":null,"permalink":"/en/network/ipv6/packet-format/","section":"Network Articles","summary":"","title":"IPv6 Packet Header Structure","type":"network"},{"content":" IPv4 Packet Header Structure An IPv4 (Internet Protocol version 4) packet consists of a header attached at the front, followed by data (the payload). The header is defined as a stack of 32-bit (4-byte) rows; the basic portion is 20 bytes, and up to 60 bytes when options are included. This article explains the role of each field.\nDescription of Each Field Field Name Size Description Version 4 bits Indicates the IP version. Fixed at 4 for IPv4. IHL (Internet Header Length) 4 bits Expresses the header length in units of 32 bits (4 bytes). The minimum value without options is 5 (= 20 bytes), and the maximum is 15 (= 60 bytes). Type of Service (DSCP + ECN) 8 bits Controls packet priority and congestion notification. The upper 6 bits are used as DSCP (Differentiated Services Code Point) and the lower 2 bits as ECN (Explicit Congestion Notification). Total Length 16 bits The total size in bytes of the packet, including the IP header and data. Can express up to 65535 bytes. Identification 16 bits A value used to identify fragments that originated from the same packet when the packet is split (fragmented). Flags 3 bits A bit sequence used for fragment control. Bit 0 is reserved (fixed at 0), bit 1 is DF (Don\u0026rsquo;t Fragment), and bit 2 is MF (More Fragments, indicating whether further fragments follow). Fragment Offset 13 bits Indicates, in units of 8 bytes, how far the fragmented data is positioned from the start of the original packet. TTL (Time To Live) 8 bits The maximum number of router hops the packet may traverse. Decremented by 1 at each router, and discarded once it reaches 0. A mechanism to prevent looping packets from persisting forever. Protocol 8 bits Indicates the type of upper-layer protocol carried in the data portion. Header Checksum 16 bits An error-detection checksum covering only the IP header. Since the TTL changes at every router, it is recalculated each time. Source Address 32 bits The source IP address of the packet. Destination Address 32 bits The destination IP address of the packet. Options Variable length (0–40 bytes) An optional field used to specify additional functionality such as security or timestamp recording. When present, padding is added to align to a 32-bit boundary. Only present when IHL is greater than 5. Data (Payload) Variable length The data body passed from an upper-layer protocol (TCP, UDP, ICMP, etc.). Common Protocol Values The value of the Protocol field indicates the type of upper-layer protocol carried in the data portion. Common values are as follows.\nProtocol Value Protocol 1 ICMP 2 IGMP 6 TCP 17 UDP 41 IPv6 (IPv6 encapsulation) 47 GRE 50 ESP (IPsec) 51 AH (IPsec) 89 OSPF 132 SCTP Protocol numbers are managed by IANA, and the full list of assigned values is published here.\nIANA - Protocol Numbers Header Length and Fragmentation IHL only represents the header length; the length of the entire packet is expressed separately by the Total Length field. Item Size Notes IP header (without options) 20 bytes The case when IHL = 5. The most common configuration. IP header (with options) 24–60 bytes The case when IHL = 6–15. Increases in increments of 4 bytes. Entire IP packet Up to 65535 bytes The upper limit expressible by the Total Length field. If the packet size is larger than the MTU (Maximum Transmission Unit) of a link along the path, the packet is fragmented by the source or a router. Fragmented packets are reassembled at the receiving end using the Identification, Flags, and Fragment Offset fields. However, if the DF bit is set, fragmentation is prohibited, and a packet exceeding the MTU is discarded, with an ICMP Destination Unreachable message returned to the source.\nRelated RFCs RFC Title Summary RFC 791 Internet Protocol The original specification for IPv4. Defines the basic format including header structure, fragmentation, and TTL. ","date":"1 August 2026","externalUrl":null,"permalink":"/en/network/ipv4/packet-format/","section":"Network Articles","summary":"","title":"IPv4 Packet Header Structure","type":"network"},{"content":" Ethernet Frame Structure A frame used in Ethernet (Ethernet II / IEEE 802.3) is made up of several fields. This article explains the role of each field and the frame size.\nDescription of Each Field Field Name Size Description Preamble 7 bytes A bit pattern that repeats 10101010 seven times. Used to synchronize the receiver\u0026rsquo;s clock with the sender\u0026rsquo;s. SFD (Start Frame Delimiter) 1 byte A fixed pattern of 10101011. Indicates that the frame body (destination MAC address) begins immediately after. Destination MAC Address 6 bytes The MAC address of the device the frame is being sent to. Broadcast (FF:FF:FF:FF:FF:FF) and multicast addresses can also be specified. Source MAC Address 6 bytes The MAC address of the device that sent the frame. Type/Length (EtherType) 2 bytes If the value is 1500 (0x05DC) or less, it represents the data length; if it is 1536 (0x0600) or more, it represents the upper-layer protocol type (EtherType). Data (Payload) 46–1500 bytes The data body passed from the upper layer. If it is less than 46 bytes, padding is added to satisfy the minimum frame length. FCS (Frame Check Sequence / CRC) 4 bytes A CRC32 checksum calculated from the content between the destination MAC address and the data. Used to detect bit errors during transmission. Common EtherType Values When the value of the Type/Length field is 1536 (0x0600) or greater, that value indicates the upper-layer protocol type (EtherType). Common values are as follows.\nEtherType Value Protocol 0x0800 IPv4 0x0806 ARP 0x8100 IEEE 802.1Q VLAN-tagged frame 0x8847 MPLS unicast 0x8848 MPLS multicast 0x8863 PPPoE Discovery Stage 0x8864 PPPoE Session Stage 0x888E IEEE 802.1X EAPOL 0x88CC LLDP 0x86DD IPv6 EtherType values are managed by the IEEE Registration Authority, and the full list of assigned values is published here.\nIEEE Registration Authority - EtherType list Frame Size The preamble and SFD are physical-layer synchronization fields and are not included in the size of the MAC frame. Range Size Notes MAC frame (destination MAC address through FCS) 64–1518 bytes The frame size as defined by the Ethernet standard. Total transmitted data (including preamble and SFD) 72–1526 bytes The size of the full bit stream actually sent over the cable. If the data is less than 46 bytes, padding is inserted to satisfy the minimum frame length of 64 bytes (MAC frame). This minimum size is required for collision detection to function correctly under CSMA/CD.\nAlso, when an 802.1Q VLAN tag is added, a 4-byte VLAN tag is inserted between the source MAC address and the Type/Length field, extending the maximum frame length to 1522 bytes.\n","date":"1 August 2026","externalUrl":null,"permalink":"/en/network/ethernet/frame-format/","section":"Network Articles","summary":"","title":"Ethernet Frame Structure","type":"network"},{"content":" Checking and Changing the Hostname This article explains how to check and change the hostname on Ubuntu 26.04 LTS Server. There are two ways to change the hostname: a permanent method that survives a reboot, and a temporary method that reverts after a reboot.\nChecking the Hostname (hostnamectl Command) Command to Check the Hostnamehostnamectl Example Output of the Hostname Check Commandkazu@ubuntu2604:~$ hostnamectl Static hostname: ubuntu2604 Icon name: computer-vm Chassis: vm 🖴 Machine ID: 4a8cf9d0938b433e8fb26a71d7d266a7 Boot ID: b37517594817444bbfa955abceb52cd2 Virtualization: kvm Operating System: Ubuntu 26.04 LTS Kernel: Linux 7.0.0-28-generic Architecture: x86-64 Hardware Vendor: QEMU Hardware Model: Ubuntu 24.04 PC _Q35 + ICH9, 2009_ Hardware Version: pc-q35-noble Firmware Version: 1.16.3-debian-1.16.3-2 Firmware Date: Tue 2014-04-01 Firmware Age: 12y 3month 2w 4d kazu@ubuntu2604:~$ Checking the Hostname (hostname Command) Command to Check the Hostnamehostname Example Output of the Hostname Check Commandkazu@ubuntu2604:~$ hostname ubuntu2604 kazu@ubuntu2604:~$ The above output is for a host whose hostname is ubuntu2604.\nChanging the Hostname (Permanent: hostnamectl Method) This method keeps the configured hostname even after a system reboot.\nCommand to Set the Hostnamesudo hostnamectl set-hostname [NAME] Field Value [NAME] Specify the hostname to set Example of Running the Hostname Set Commandkazu@ubuntu2604:~$ sudo hostnamectl set-hostname webserver kazu@ubuntu2604:~$ hostnamectl Static hostname: webserver Icon name: computer-vm Chassis: vm 🖴 Machine ID: 4a8cf9d0938b433e8fb26a71d7d266a7 Boot ID: b37517594817444bbfa955abceb52cd2 Virtualization: kvm Operating System: Ubuntu 26.04 LTS Kernel: Linux 7.0.0-28-generic Architecture: x86-64 Hardware Vendor: QEMU Hardware Model: Ubuntu 24.04 PC _Q35 + ICH9, 2009_ Hardware Version: pc-q35-noble Firmware Version: 1.16.3-debian-1.16.3-2 Firmware Date: Tue 2014-04-01 Firmware Age: 12y 3month 2w 4d kazu@ubuntu2604:~$ The above is an example of changing the hostname to webserver. The prompt doesn\u0026rsquo;t update immediately — it will reflect the change after you log in again. With this method, the hostname remains changed even after a reboot.\nChanging the Hostname (Temporary: hostname Method) This method is a temporary change and is not permanent. Command to Set the Hostnamesudo hostname [NAME] Field Value [NAME] Specify the hostname to set Example of Running the Hostname Set Commandkazu@ubuntu2604:~$ sudo hostname dbserver kazu@ubuntu2604:~$ hostname dbserver kazu@ubuntu2604:~$ The above is an example of temporarily changing the hostname to dbserver. The prompt doesn\u0026rsquo;t update immediately — it will reflect the change after you log in again. After a reboot, the hostname reverts to what it was before the change.\n","date":"18 July 2026","externalUrl":null,"permalink":"/en/linux/ubuntu2604/hostname/","section":"Linux Articles","summary":"","title":"Changing the Hostname on Ubuntu 26.04 LTS Server","type":"linux"},{"content":" How to Configure the Hostname on Cisco IOS XR The command for setting the hostname on Cisco IOS XR.\nCisco IOS XR Hostname Configurationhostname [HOSTNAME] Field Value [HOSTNAME] Specify the hostname to set Example: Changing the Cisco IOS XR Hostname This example changes the hostname from ios to IOS-XR. After the commit, you can see the prompt change from ios to IOS-XR.\nHostname Change ExampleRP/0/RP0/CPU0:ios#configure Sat Aug 1 09:33:37.759 UTC RP/0/RP0/CPU0:ios(config)#hostname IOS-XR RP/0/RP0/CPU0:ios(config)#commit Sat Aug 1 09:33:45.834 UTC RP/0/RP0/CPU0:IOS-XR(config)#end RP/0/RP0/CPU0:IOS-XR# Related Articles IOS XR Basic Configuration IOS XR Hostname Configuration (hostname) IOS XR Interface Configuration (shutdown/no shutdown) and Verification ","date":"18 July 2026","externalUrl":null,"permalink":"/en/routerswitch/ios-xr/hostname/","section":"Router and Switch Articles","summary":"","title":"IOS XR Hostname Configuration (hostname)","type":"routerswitch"},{"content":" Classification of IPv4 Addresses An IPv4 address is represented as 32 bits and is classified into several types depending on its purpose and allocation range. Historically, addresses were classified by class (A through E), but today classless addressing based on CIDR (Classless Inter-Domain Routing) is the mainstream approach. In addition, special-purpose address ranges are defined, such as global/private, loopback, link-local, and shared addresses.\nClassful Addressing (Class A–E) Classful addressing is a historical classification; current routing uses the classless approach defined by CIDR. Class Leading Bits Address Range Default Subnet Mask Purpose Class A 0 0.0.0.0 – 127.255.255.255 255.0.0.0 (/8) Unicast addresses for large-scale networks. Class B 10 128.0.0.0 – 191.255.255.255 255.255.0.0 (/16) Unicast addresses for medium-scale networks. Class C 110 192.0.0.0 – 223.255.255.255 255.255.255.0 (/24) Unicast addresses for small-scale networks. Class D 1110 224.0.0.0 – 239.255.255.255 None (no concept of a mask) Reserved for multicast addresses. Class E 1111 240.0.0.0 – 255.255.255.255 None (no concept of a mask) Reserved for experimental future use. Classes A through C are defined as unicast addresses for hosts, and the boundary between the network portion and host portion (the classful mask) is determined by the pattern of the leading bits. Class D is reserved exclusively for multicast, and Class E is reserved for experimental use; neither is assigned to ordinary hosts.\nGlobal Addresses (Public Addresses) These are addresses whose uniqueness is guaranteed across the internet and that can be routed directly on the internet. They are allocated by IANA (Internet Assigned Numbers Authority) through the Regional Internet Registries (RIRs) to ISPs and organizations, and correspond to the ranges remaining after excluding special-purpose blocks such as private addresses and loopback addresses described below.\nPrivate Addresses These are address ranges reserved for use within local networks that are not directly connected to the internet, such as inside an organization. These addresses are not routed on the internet and can be reused independently by multiple organizations.\nClass Equivalent Address Range CIDR Notation Number of Addresses Class A 10.0.0.0 – 10.255.255.255 10.0.0.0/8 About 16.77 million Class B 172.16.0.0 – 172.31.255.255 172.16.0.0/12 About 1.04 million Class C 192.168.0.0 – 192.168.255.255 192.168.0.0/16 65,536 Loopback Address This is an address reserved to refer to the host itself. Packets addressed to the loopback address are processed internally by the host without passing through a network interface. In IPv4, the entire 127.0.0.0/8 block is reserved for loopback use, although 127.0.0.1 is typically used as the representative address.\nItem Value Address Range 127.0.0.0 – 127.255.255.255 CIDR Notation 127.0.0.0/8 Representative Address 127.0.0.1 Link-Local Address This is an address valid only within the same link (the same segment), used when a host automatically assigns itself an address (APIPA: Automatic Private IP Addressing) because it was unable to obtain one from a DHCP server or similar. Packets addressed to or originating from a link-local address are not forwarded beyond a router.\nItem Value Address Range 169.254.0.0 – 169.254.255.255 CIDR Notation 169.254.0.0/16 Shared Address Space This is an address space reserved for use within an ISP\u0026rsquo;s own network in Carrier-Grade NAT (CGN / CGNAT) environments. It occupies a position similar to private addresses (RFC 1918), but was newly defined to avoid address collisions in cases where both the ISP\u0026rsquo;s equipment and customer-premises equipment use RFC 1918 addresses.\nItem Value Address Range 100.64.0.0 – 100.127.255.255 CIDR Notation 100.64.0.0/10 Primary Use Carrier-Grade NAT (CGN) within an ISP\u0026rsquo;s network Related RFCs RFC Title Summary RFC 791 Internet Protocol The original specification for IPv4. Defines the Class A–C address scheme. RFC 1112 Host Extensions for IP Multicasting Defines Class D as the multicast address range. RFC 1918 Address Allocation for Private Internets Defines the private address ranges (10/8, 172.16/12, 192.168/16). RFC 1122 Requirements for Internet Hosts \u0026ndash; Communication Layers Specifies 127.0.0.0/8 as the loopback address range. RFC 3927 Dynamic Configuration of IPv4 Link-Local Addresses Defines 169.254.0.0/16 as the link-local address range. RFC 6598 IANA-Reserved IPv4 Prefix for Shared Address Space Defines 100.64.0.0/10 as the shared address space for Carrier-Grade NAT. RFC 4632 Classless Inter-Domain Routing (CIDR) Replaces classful addressing with the classless routing scheme (CIDR). RFC 6890 Special-Purpose IP Address Registries Specifies the registry for special-purpose addresses such as loopback and link-local. ","date":"2 August 2026","externalUrl":null,"permalink":"/en/network/ipv4/address/","section":"Network Articles","summary":"","title":"IPv4 Addresses","type":"network"},{"content":" Classification of IPv6 Addresses An IPv6 address is represented as 128 bits and is classified into several types depending on its purpose and scope. Unlike IPv4, there is no classful division (Class A–E); instead, the type of an address is determined by its leading bit pattern (prefix). Representative types include the global unicast address, unique local address (the private-address equivalent), loopback address, link-local address, and multicast address.\nAllocation of the Address Space There is no classful division as in IPv4. Each address type is identified by its prefix (leading bit pattern). Type Prefix Purpose Global Unicast Address 2000::/3 A unicast address routable on the internet. Unique Local Address fc00::/7 An address for environments not directly connected to the internet, such as an organization\u0026rsquo;s internal network (the private-address equivalent). Link-Local Address fe80::/10 An address valid only within the same link. Multicast Address ff00::/8 An address used for one-to-many communication (the equivalent of Class D in IPv4). Loopback Address ::1/128 An address that refers to the host itself. Unspecified Address ::/128 A special address indicating that no address has been determined. Global Address (Global Unicast Address) This is an address whose uniqueness is guaranteed across the internet and that can be routed directly on the internet. The 2000::/3 range is allocated by IANA through the Regional Internet Registries (RIRs) to ISPs and organizations, and it is typically composed of a 64-bit network prefix in the upper bits and a 64-bit interface ID in the lower bits.\nUnique Local Address (Private-Address Equivalent) This is an address defined for use within local networks that are not directly connected to the internet, such as inside an organization. It occupies a position equivalent to IPv4\u0026rsquo;s private addresses (RFC 1918) and is not routed on the internet.\nItem Value Prefix fc00::/7 Local (L) bit = 1 (in practical use) fd00::/8 Local (L) bit = 0 (reserved for future definition) fc00::/8 Global ID A 40-bit random value that, in practice, avoids collisions between organizations. Loopback Address This is an address reserved to refer to the host itself. Packets addressed to the loopback address are processed internally by the host without passing through a network interface. Unlike IPv4\u0026rsquo;s 127.0.0.0/8, IPv6 assigns only a single address per host.\nItem Value Address ::1/128 Link-Local Address This is an address valid only within the same link (the same segment). It is automatically assigned to every IPv6-enabled interface and is used for control communication within the link, such as Neighbor Discovery and router discovery. Packets addressed to or originating from a link-local address are not forwarded beyond a router.\nItem Value Prefix fe80::/10 Range in practical use fe80::/64 (the lower 64 bits are used as the interface ID) Multicast Address This is an address used for one-to-many communication, corresponding to Class D in IPv4. It is also used as a replacement mechanism for IPv4 broadcast, and is characterized by having flag and scope fields embedded within it.\nItem Value Prefix ff00::/8 Example: all-nodes multicast (link-local) ff02::1 Example: all-routers multicast (link-local) ff02::2 Unspecified Address This is a special address indicating that an address has not yet been determined. It is used during communication that temporarily lacks a source address, such as in the process of Duplicate Address Detection (DAD), and it cannot be used as a packet\u0026rsquo;s destination.\nItem Value Address ::/128 Related RFCs RFC Title Summary RFC 4291 IP Version 6 Addressing Architecture The original specification for IPv6 addressing. Defines the global unicast, link-local, loopback, unspecified, and multicast address types. RFC 4193 Unique Local IPv6 Unicast Addresses Defines fc00::/7 as the unique local address range (the private-address equivalent). RFC 4007 IPv6 Scoped Address Architecture Defines the zone concept for scoped addresses such as link-local addresses. RFC 3587 IPv6 Global Unicast Address Format Defines the format of the global unicast address (network prefix and interface ID). RFC 6890 Special-Purpose IP Address Registries Specifies the registry for special-purpose addresses in both IPv4 and IPv6. ","date":"2 August 2026","externalUrl":null,"permalink":"/en/network/ipv6/address/","section":"Network Articles","summary":"","title":"IPv6 Addresses","type":"network"},{"content":" Updating the System with apt APT is the standard software package manager used on Ubuntu. To upgrade the system, run the following commands in the order update, then upgrade.\nRefreshing the Package List (apt update) Command to Refresh the Package Listsudo apt update Example of Refreshing the Package List (apt update)kazu@ubuntu2604:~$ sudo apt update [sudo: authenticate] Password: Hit:1 http://security.ubuntu.com/ubuntu resolute-security InRelease Hit:2 http://jp.archive.ubuntu.com/ubuntu resolute InRelease Hit:3 http://jp.archive.ubuntu.com/ubuntu resolute-updates InRelease Hit:4 http://jp.archive.ubuntu.com/ubuntu resolute-backports InRelease 35 packages can be upgraded. Run \u0026#39;apt list --upgradable\u0026#39; to see them. kazu@ubuntu2604:~$ Upgrading System Packages (apt upgrade) Command to Upgrade System Packagessudo apt -y upgrade The -y option automatically answers Y to all (Yes/No) confirmation prompts. Example of Upgrading System Packages (apt upgrade)kazu@ubuntu2604:~$ sudo apt -y upgrade [sudo: authenticate] Password: The following packages were automatically installed and are no longer required: linux-headers-7.0.0-14 linux-modules-7.0.0-14-generic linux-headers-7.0.0-14-generic linux-tools-7.0.0-14 linux-image-unsigned-7.0.0-14-generic linux-tools-7.0.0-14-generic linux-main-modules-zfs-7.0.0-14-generic Use \u0026#39;sudo apt autoremove\u0026#39; to remove them. Upgrading: base-files linux-firmware-qualcomm-graphics fwupd linux-firmware-qualcomm-misc gir1.2-packagekitglib-1.0 linux-firmware-realtek iproute2 motd-news-config libfwupd3 packagekit libgcrypt20 python3-distupgrade libpackagekit-glib2-18 sg3-utils libsgutils2-1.48 sg3-utils-udev linux-firmware-amd-misc snapd linux-firmware-broadcom-wireless ubuntu-kernel-accessories linux-firmware-intel-graphics ubuntu-minimal linux-firmware-intel-wireless ubuntu-release-upgrader-core linux-firmware-marvell-wireless ubuntu-server linux-firmware-mellanox-spectrum ubuntu-server-minimal linux-firmware-netronome ubuntu-standard linux-firmware-nvidia-graphics update-notifier-common linux-firmware-qlogic /snip/ Processing triggers for plymouth-theme-ubuntu-text (24.004.60+git20250831.4a3c171d-0ubuntu8)… Processing triggers for dracut (110-11)… update-initramfs: Generating /boot/initrd.img-7.0.0-28-generic Scanning processes... Scanning linux images... Running kernel seems to be up-to-date. No services need to be restarted. No containers need to be restarted. No user sessions are running outdated binaries. No VM guests are running outdated hypervisor (qemu) binaries on this host. kazu@ubuntu2604:~$ References Ubuntu Server documentation: Managing your software\n","date":"19 July 2026","externalUrl":null,"permalink":"/en/linux/ubuntu2604/apt_update_upgrade/","section":"Linux Articles","summary":"","title":"Ubuntu 26.04 LTS Server System Optimization with apt update/upgrade","type":"linux"},{"content":" How to shutdown / no shutdown an Interface on Cisco IOS XR These are the commands for disabling and enabling an interface on Cisco IOS XR. Run them in interface configuration mode.\nCisco IOS XR Interface shutdown Configurationinterface [INTERFACE_NAME] shutdown Cisco IOS XR Interface no shutdown Configurationinterface [INTERFACE_NAME] no shutdown Field Value [INTERFACE_NAME] Specify the target interface name (e.g. GigabitEthernet0/0/0/0) Example: Configuring Interface shutdown This example shuts down GigabitEthernet0/0/0/0.\nInterface shutdown ExampleRP/0/RP0/CPU0:IOX-XR#configure Sat Aug 1 14:33:16.300 UTC RP/0/RP0/CPU0:IOX-XR(config)#interface gigabitEthernet 0/0/0/0 RP/0/RP0/CPU0:IOX-XR(config-if)#shutdown RP/0/RP0/CPU0:IOX-XR(config-if)#commit Sat Aug 1 14:33:26.622 UTC RP/0/RP0/CPU0:IOX-XR(config-if)#end RP/0/RP0/CPU0:IOX-XR# Example: Configuring Interface no shutdown This example sets no shutdown on GigabitEthernet0/0/0/0.\nInterface no shutdown ExampleRP/0/RP0/CPU0:IOX-XR#configure Sat Aug 1 14:34:45.321 UTC RP/0/RP0/CPU0:IOX-XR(config)#interface gigabitEthernet 0/0/0/0 RP/0/RP0/CPU0:IOX-XR(config-if)#no shutdown RP/0/RP0/CPU0:IOX-XR(config-if)#commit Sat Aug 1 14:34:54.061 UTC RP/0/RP0/CPU0:IOX-XR(config-if)#end RP/0/RP0/CPU0:IOX-XR# Checking Interface State with show interfaces You can check the state of an interface with the show interfaces command.\nCisco IOS XR show interfaces Commandshow interfaces [INTERFACE_NAME] Field Value [INTERFACE_NAME] Specify the interface name to check the state of (if omitted, all interfaces are shown) Example: Checking the shutdown State When shutdown is configured, it is shown as administratively down.\nshow interfaces Example (shutdown State)RP/0/RP0/CPU0:IOX-XR#show interfaces gigabitEthernet 0/0/0/0 GigabitEthernet0/0/0/0 is administratively down, line protocol is administratively down Interface state transitions: 2 Hardware is GigabitEthernet, address is 5254.0047.fbf7 (bia 5254.0047.fbf7) Description: to GigabitEthernet0/0/0/0.xrd-1 Internet address is Unknown MTU 1514 bytes, BW 1000000 Kbit (Max: 1000000 Kbit) reliability 255/255, txload 0/255, rxload 0/255 Encapsulation ARPA, Full-duplex, 1000Mb/s, unknown, link type is force-up output flow control is off, input flow control is off Carrier delay (up) is 10 msec loopback not set, -- snip -- RP/0/RP0/CPU0:IOX-XR# Example: Checking the no shutdown (Operating Normally) State After no shutdown is configured, if the link is connected it is shown as up / up.\nshow interfaces Example (up State)RP/0/RP0/CPU0:IOX-XR#show interfaces gigabitEthernet 0/0/0/0 GigabitEthernet0/0/0/0 is up, line protocol is up Interface state transitions: 3 Hardware is GigabitEthernet, address is 5254.0047.fbf7 (bia 5254.0047.fbf7) Description: to GigabitEthernet0/0/0/0.xrd-1 Internet address is Unknown MTU 1514 bytes, BW 1000000 Kbit (Max: 1000000 Kbit) reliability 255/255, txload 0/255, rxload 0/255 Encapsulation ARPA, Full-duplex, 1000Mb/s, unknown, link type is force-up output flow control is off, input flow control is off Carrier delay (up) is 10 msec loopback not set, -- snip -- RP/0/RP0/CPU0:IOX-XR# Example: Checking the State When no shutdown Is Set but the Cable Is Not Connected Even with no shutdown configured, if the carrier signal cannot be detected — for example because the cable is disconnected or no SFP is inserted — the interface is shown as is down, line protocol is down, unlike the shutdown state (note that administratively is not present).\nshow interfaces Example (Cable Not Connected)RP/0/RP0/CPU0:IOX-XR#show interfaces gigabitEthernet 0/0/0/0 GigabitEthernet0/0/0/0 is down, line protocol is down Interface state transitions: 2 Hardware is GigabitEthernet, address is 5254.0047.fbf7 (bia 5254.0047.fbf7) Description: to GigabitEthernet0/0/0/0.xrd-1 Internet address is Unknown MTU 1514 bytes, BW 1000000 Kbit (Max: 1000000 Kbit) reliability 255/255, txload 0/255, rxload 0/255 Encapsulation ARPA, Full-duplex, 1000Mb/s, unknown, link type is force-up output flow control is off, input flow control is off Carrier delay (up) is 10 msec loopback not set, -- snip -- RP/0/RP0/CPU0:IOX-XR# The first line, is up, line protocol is up, actually shows two separate states.\nPosition Meaning First (is up / is down / is administratively down) Layer 1 (physical) state. Reflects the shutdown/no shutdown configuration and carrier (line signal) detection status Second (line protocol is up / down) Layer 2 (data link) state. If the first is down, this also goes down accordingly Combining these two values lets you distinguish between different causes.\nFirst State Second State Meaning administratively down administratively down Disabled by shutdown configuration down down no shutdown is configured, but a carrier signal cannot be detected due to a disconnected cable, missing SFP, etc. up up no shutdown is configured and the link is also up normally administratively down and down look similar at a glance, but the difference is that the former is caused by configuration (shutdown), while the latter is caused by a physical factor (disconnection, etc.). Checking show running-config alongside this lets you determine which is the cause.\nUsing the show interfaces brief command, you can check the state of all interfaces concisely, one line each.\nshow interfaces brief Example RP/0/RP0/CPU0:IOX-XR#show interfaces brief Sat Aug 1 14:36:32.883 UTC Intf Intf LineP Encap MTU BW Name State State Type (byte) (Kbps) -------------------------------------------------------------------------------- Lo0 admin-down admin-down Loopback 1500 0 Nu0 up up Null 1500 0 Mg0/RP0/CPU0/0 admin-down admin-down ARPA 1514 1000000 Gi0/0/0/0 up up ARPA 1514 1000000 Gi0/0/0/1 down down ARPA 1514 1000000 Gi0/0/0/2 admin-down admin-down ARPA 1514 1000000 RP/0/RP0/CPU0:IOX-XR# Gi0/0/0/1 has no shutdown configured, but both Intf State and LineP State are down, suggesting a disconnected cable, missing SFP, or similar. Note that this has a different meaning from Gi0/0/0/2\u0026rsquo;s admin-down (shutdown configured).\nDifference in How shutdown / no shutdown Appear in show running-config When checking the configuration with show running-config, note that shutdown and no shutdown are displayed differently.\nWhen shutdown is configured: a shutdown line is shown within the interface configuration When no shutdown is configured: a no shutdown line is not shown (the absence of the setting is treated as meaning the interface is enabled) show running-config Example for the shutdown State show running-config Example (shutdown State)RP/0/RP0/CPU0:IOX-XR#show running-config interface gigabitEthernet 0/0/0/0 interface GigabitEthernet0/0/0/0 description to-IOS-XE ipv4 address 10.0.0.1 255.255.255.252 shutdown ! RP/0/RP0/CPU0:IOX-XR# show running-config Example for the no shutdown State show running-config Example (no shutdown State)RP/0/RP0/CPU0:IOX-XR#show running-config interface gigabitEthernet 0/0/0/0 interface GigabitEthernet0/0/0/0 description to-IOS-XE ipv4 address 10.0.0.1 255.255.255.252 ! RP/0/RP0/CPU0:IOX-XR# In the no shutdown state, the shutdown line itself does not exist, so only the other settings appear in show running-config. When checking whether an interface has been unintentionally shut down, it\u0026rsquo;s a good idea to check whether shutdown appears in show running-config.\nRelated Articles IOS XR Basic Configuration IOS XR Hostname Configuration (hostname) IOS XR Interface Configuration (shutdown/no shutdown) and Verification ","date":"18 July 2026","externalUrl":null,"permalink":"/en/routerswitch/ios-xr/interface/","section":"Router and Switch Articles","summary":"","title":"IOS XR Interface Configuration (shutdown/no shutdown) and Verification","type":"routerswitch"},{"content":" Checking and Changing the Timezone This article explains how to check the current timezone on Ubuntu 26.04 LTS Server and how to change it to Japan Standard Time (JST).\nHow to Check the Current Timezone Command to Check the Timezonetimedatectl Example Output of the Timezone Check Commandkazu@ubuntu2604:~$ timedatectl Local time: Sun 2026-07-19 08:06:50 UTC Universal time: Sun 2026-07-19 08:06:50 UTC RTC time: Sun 2026-07-19 08:06:50 Time zone: Etc/UTC (UTC, +0000) System clock synchronized: yes NTP service: active RTC in local TZ: no kazu@ubuntu2604:~$ How to Change the Timezone to Japan (JST) Command to Change the Timezone to Japan (JST)sudo timedatectl set-timezone Asia/Tokyo Example of Changing the Timezone to Japan (JST)kazu@ubuntu2604:~$ sudo timedatectl set-timezone Asia/Tokyo [sudo: authenticate] Password: kazu@ubuntu2604:~$ date Sun Jul 19 05:10:05 PM JST 2026 kazu@ubuntu2604:~$ timedatectl Local time: Sun 2026-07-19 17:10:13 JST Universal time: Sun 2026-07-19 08:10:13 UTC RTC time: Sun 2026-07-19 08:10:13 Time zone: Asia/Tokyo (JST, +0900) System clock synchronized: yes NTP service: active RTC in local TZ: no kazu@ubuntu2604:~$ date Sun Jul 19 05:10:14 PM JST 2026 kazu@ubuntu2604:~$ Listing Available Timezones Example of Listing Available Timezoneskazu@ubuntu2604:~$ timedatectl list-timezones Africa/Abidjan Africa/Accra Africa/Addis_Ababa Africa/Algiers Africa/Asmara Africa/Bamako Africa/Bangui Africa/Banjul / snip / ","date":"18 July 2026","externalUrl":null,"permalink":"/en/linux/ubuntu2604/timezone/","section":"Linux Articles","summary":"","title":"Changing the Timezone to Japan Standard Time (JST) on Ubuntu 26.04 LTS Server","type":"linux"},{"content":" Installing the Latest Version of neovim This article explains the steps for installing the latest version of neovim from the official site.\nDownloading and Installing neovim These steps download the latest release and extract it under /opt.\nDownload and Install Commandscurl -LO https://github.com/neovim/neovim/releases/latest/download/nvim-linux-x86_64.tar.gz sudo rm -rf /opt/nvim-linux-x86_64 sudo tar -C /opt -xzf nvim-linux-x86_64.tar.gz Example of Downloading and Installingkazu@ubuntu2604:~$ curl -LO https://github.com/neovim/neovim/releases/latest/download/nvim-linux-x86_64.tar.gz % Total % Received % Xferd Average Speed Time Time Time Current Dload Upload Total Spent Left Speed 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 100 10.87M 100 10.87M 0 0 16.51M 0 0 kazu@ubuntu2604:~$ sudo rm -rf /opt/nvim-linux-x86_64 kazu@ubuntu2604:~$ sudo tar -C /opt -xzf nvim-linux-x86_64.tar.gz kazu@ubuntu2604:~$ ls -ltr /opt total 4 drwxr-xr-x 5 root root 4096 Jul 19 18:34 nvim-linux-x86_64 kazu@ubuntu2604:~$ The downloaded nvim-linux-x86_64.tar.gz file remains in the directory where you ran the command — delete it if you no longer need it.\nSetting the PATH Environment Variable Since neovim is installed under /opt, add it to your PATH.\nSetting the PATH Environment Variableecho \u0026#39;export PATH=\u0026#34;$PATH:/opt/nvim-linux-x86_64/bin\u0026#34;\u0026#39; \u0026gt;\u0026gt; ~/.bashrc source ~/.bashrc Launching neovim Command to Launch nvimnvim Example of Running nvimkazu@ubuntu2604:~$ nvim ~ ~ ~ ~ │ ╲ ││ ~ ││╲╲││ ~ ││ ╲ │ ~ ~ NVIM v0.12.4 ~ ──────────────────────────────────────────── ~ Nvim is open source and freely distributable ~ https://neovim.io/#chat ~ ──────────────────────────────────────────── ~ type :help nvim\u0026lt;Enter\u0026gt; if you are new! ~ type :checkhealth\u0026lt;Enter\u0026gt; to optimize Nvim ~ type :q\u0026lt;Enter\u0026gt; to exit ~ type :help\u0026lt;Enter\u0026gt; for help ~ ──────────────────────────────────────────── ~ type :help news\u0026lt;Enter\u0026gt; for v0.12 notes ~ ──────────────────────────────────────────── ~ Help poor children in Uganda! ~ type :help Kuwasha\u0026lt;Enter\u0026gt; for information ~ ~ [No Name] 0,0-1 All References 【Official Site】neovim Install\n","date":"19 July 2026","externalUrl":null,"permalink":"/en/linux/ubuntu2604/neovim-install/","section":"Linux Articles","summary":"","title":"How to Install the Latest neovim from the Official Site on Ubuntu 26.04 LTS Server","type":"linux"},{"content":"","date":"2 August 2026","externalUrl":null,"permalink":"/en/categories/","section":"Categories","summary":"","title":"Categories","type":"categories"},{"content":"","date":"2 August 2026","externalUrl":null,"permalink":"/en/categories/ipv4/","section":"Categories","summary":"","title":"IPv4","type":"categories"},{"content":"","date":"2 August 2026","externalUrl":null,"permalink":"/en/categories/ipv6/","section":"Categories","summary":"","title":"IPv6","type":"categories"},{"content":"Technical notes and memos.\nNetworking Ethernet IPv4 IPv6 Network Devices Cisco IOS XR Linux Ubuntu26.04 ","date":"2 August 2026","externalUrl":null,"permalink":"/en/","section":"Welcome to KAZULOG!","summary":"","title":"Welcome to KAZULOG!","type":"page"},{"content":"","date":"2 August 2026","externalUrl":null,"permalink":"/en/categories/cisco-ios-xr/","section":"Categories","summary":"","title":"Cisco IOS XR","type":"categories"},{"content":" IOS XR Config Reset Running commit replace after configure empties the running-config, resetting the configuration. Before it executes, you\u0026rsquo;ll be asked Do you wish to proceed? [no]:; enter y to proceed.\nCisco IOS XR Config Reset Procedureconfigure commit replace IOS XR Config Reset Example Cisco IOS XR Config Reset ExampleRP/0/RP0/CPU0:xr01#show running-config hostname Sun Aug 2 02:48:34.609 UTC ! IOS XRv 9000 Config generated on 2026-08-02 00:49 ! by ank-ng hostname xr01 RP/0/RP0/CPU0:xr01#configure Sun Aug 2 02:48:43.740 UTC !!! After entering config mode, running commit replace replaces the config with an empty one RP/0/RP0/CPU0:xr01(config)#commit replace Sun Aug 2 02:48:56.029 UTC This commit will replace or remove the entire running configuration. This operation can be service affecting. Do you wish to proceed? [no]: y RP/0/RP0/CPU0:Aug 2 02:49:03.930 UTC: ifmgr[237]: %PKT_INFRA-LINK-3-UPDOWN : Interface MgmtEth0/RP0/CPU0/0, changed state to Down RP/0/RP0/CPU0:Aug 2 02:49:04.970 UTC: ifmgr[237]: %PKT_INFRA-LINK-3-UPDOWN : Interface MgmtEth0/RP0/CPU0/0, changed state to Up !!!! After a moment the config is reset and the prompt changes to the default \u0026#34;ios\u0026#34; RP/0/RP0/CPU0:ios(config)# RP/0/RP0/CPU0:ios(config)#end RP/0/RP0/CPU0:ios#show running-config Sun Aug 2 02:50:10.385 UTC !! Building configuration... !! IOS XR Configuration 26.1.1 !! Last configuration change at Sun Aug 2 02:49:02 2026 by cisco ! end RP/0/RP0/CPU0:ios# Related Articles IOS XR Operation Methods IOS XR Two-Stage Commit Model IOS XR Config Reset ","date":"2 August 2026","externalUrl":null,"permalink":"/en/routerswitch/ios-xr/config-reset/","section":"Router and Switch Articles","summary":"","title":"IOS XR Config Reset","type":"routerswitch"},{"content":" About the Two-Stage Commit Model Cisco IOS XR uses a Two-Stage Commit model that separates configuration changes into a \u0026ldquo;Target Configuration (first stage)\u0026rdquo; and a \u0026ldquo;Commit to the Running Configuration (second stage)\u0026rdquo;.\nFirst stage: What the user enters under configure is first applied to their own private Target Configuration. At this point the Running Configuration is not affected, and any syntax errors can be corrected before committing. Second stage (Commit): Running commit applies the contents of the Target Configuration to the Running Configuration all at once. Whereas a single-stage model that applies each line immediately risks ending up in an inconsistent state if only part of the configuration is applied, Two-Stage Commit lets you validate and apply changes together as a batch.\nIOS XR Configuration Example This example configures ipv4 192.168.10.1/24 on interface GigabitEthernet0/0/0/0.\nCisco IOS XR Configuration ExampleRP/0/RP0/CPU0:xr01#configure RP/0/RP0/CPU0:xr01(config)#show running-config interface GigabitEthernet0/0/0/0 !!!! No IPv4 address configured yet (current Running state) interface GigabitEthernet0/0/0/0 description to GigabitEthernet0/0/0/0.XR02 ! RP/0/RP0/CPU0:xr01(config)#interface GigabitEthernet0/0/0/0 RP/0/RP0/CPU0:xr01(config-if)#ipv4 address 192.168.10.1 255.255.255.0 RP/0/RP0/CPU0:xr01(config-if)#exit RP/0/RP0/CPU0:xr01(config)#show configuration !!!! show configuration only shows the uncommitted diff !! Building configuration... !! IOS XR Configuration 26.1.1 interface GigabitEthernet0/0/0/0 ipv4 address 192.168.10.1 255.255.255.0 ! end RP/0/RP0/CPU0:xr01(config)#show configuration merge interface GigabitEthernet0/0/0/0 !!!! show configuration merge shows the merged result of the Target Configuration and Running interface GigabitEthernet0/0/0/0 description to GigabitEthernet0/0/0/0.XR02 ipv4 address 192.168.10.1 255.255.255.0 ! RP/0/RP0/CPU0:xr01(config)#show running-config interface GigabitEthernet0/0/0/0 !!! Not committed yet, so Running is unchanged interface GigabitEthernet0/0/0/0 description to GigabitEthernet0/0/0/0.XR02 ! RP/0/RP0/CPU0:xr01(config)#commit RP/0/RP0/CPU0:xr01(config)#end RP/0/RP0/CPU0:xr01#show running-config interface gigabitEthernet 0/0/0/0 !!! Committed, so it is now reflected in Running interface GigabitEthernet0/0/0/0 description to GigabitEthernet0/0/0/0.XR02 ipv4 address 192.168.10.1 255.255.255.0 ! RP/0/RP0/CPU0:xr01# Related Articles IOS XR Operation Methods IOS XR Two-Stage Commit Model IOS XR Config Reset ","date":"2 August 2026","externalUrl":null,"permalink":"/en/routerswitch/ios-xr/two-stage-commit/","section":"Router and Switch Articles","summary":"","title":"IOS XR Two-Stage Commit Model","type":"routerswitch"},{"content":" Ethernet Ethernet Frame Structure ","date":"1 August 2026","externalUrl":null,"permalink":"/en/network/ethernet/","section":"Network Articles","summary":"","title":"Ethernet Articles","type":"network"},{"content":" IPv4 IPv4 Packet Header Structure IPv4 Addresses ","date":"1 August 2026","externalUrl":null,"permalink":"/en/network/ipv4/","section":"Network Articles","summary":"","title":"IPv4 Articles","type":"network"},{"content":" IPv6 IPv6 Packet Header Structure IPv6 Addresses ","date":"1 August 2026","externalUrl":null,"permalink":"/en/network/ipv6/","section":"Network Articles","summary":"","title":"IPv6 Articles","type":"network"},{"content":"","date":"1 August 2026","externalUrl":null,"permalink":"/en/categories/ethernet/","section":"Categories","summary":"","title":"Ethernet","type":"categories"},{"content":"","date":"19 July 2026","externalUrl":null,"permalink":"/en/categories/ubuntu26.04/","section":"Categories","summary":"","title":"Ubuntu26.04","type":"categories"},{"content":" Privacy Policy Use of Personal Information This blog may ask visitors to provide personal information such as their name and email address when submitting an inquiry or commenting on an article. Any personal information collected is used only to respond to inquiries or to contact visitors by email when necessary, and will not be used for any other purpose.\nAbout Advertising This blog uses third-party advertising services (Google AdSense, A8.net, ValueCommerce) and uses cookies to display advertisements for products and services tailored to users\u0026rsquo; interests.\nThe use of cookies allows this site to identify your computer, but it does not identify you personally.\nFor information on how to disable cookies and details about Google AdSense, please see \u0026ldquo;Advertising – Policies \u0026amp; Terms – Google\u0026rdquo;.\nThis site is a participant in the Amazon Associates Program and the Rakuten Affiliate Program, affiliate advertising programs designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.co.jp and Rakuten.\nAbout Access Analysis Tools This blog uses \u0026ldquo;Google Analytics,\u0026rdquo; an access analysis tool provided by Google. Google Analytics uses cookies to collect traffic data. Traffic data is collected anonymously and does not identify individuals.\nAbout Inquiries When you submit an inquiry to this blog, your IP address is collected. This is a standard feature supported by the blog platform, and this IP address is not used for any purpose other than responding to spam or abuse.\nDisclaimer This blog assumes no responsibility for the information, services, etc. provided by sites reached via links or banners from this blog.\nWhile we make every effort to provide accurate information regarding the content and information on this blog, we do not guarantee its accuracy or safety. Information may also become outdated.\nPlease note that we cannot be held responsible for any damages arising from the content published on this site.\nCopyright Unauthorized reproduction of the text, images, and other content published on this blog is prohibited.\nThis blog is not intended to infringe on any copyrights or portrait rights. If you have any concerns regarding copyright or portrait rights, please contact us via the inquiry form. We will respond promptly.\n","date":"19 July 2026","externalUrl":null,"permalink":"/en/privacy/","section":"Welcome to KAZULOG!","summary":"","title":"Privacy Policy / Disclaimer / Copyright","type":"page"},{"content":" Ubuntu 26.04 Configuration Changing the Hostname on Ubuntu 26.04 LTS Server Ubuntu 26.04 LTS Server System Optimization with apt update/upgrade Changing the Timezone to Japan Standard Time (JST) on Ubuntu 26.04 LTS Server How to Install the Latest neovim from the Official Site on Ubuntu 26.04 LTS Server Ubuntu Official Pages Ubuntu Official Site Ubuntu Documentation directory ","date":"18 July 2026","externalUrl":null,"permalink":"/en/linux/ubuntu2604/","section":"Linux Articles","summary":"","title":"Ubuntu 26.04 LTS Server","type":"linux"},{"content":" IOS XR Operation Methods IOS XR Two-Stage Commit Model IOS XR Config Reset IOS XR Basic Configuration IOS XR Hostname Configuration (hostname) IOS XR Interface Configuration (shutdown/no shutdown) and Verification ","date":"18 July 2026","externalUrl":null,"permalink":"/en/routerswitch/ios-xr/","section":"Router and Switch Articles","summary":"","title":"IOS-XR","type":"routerswitch"},{"content":" Ubuntu 26.04 LTS Server ","date":"18 July 2026","externalUrl":null,"permalink":"/en/linux/","section":"Linux Articles","summary":"","title":"Linux Articles","type":"linux"},{"content":" Ethernet IPv4 IPv6 ","date":"18 July 2026","externalUrl":null,"permalink":"/en/network/","section":"Network Articles","summary":"","title":"Network Articles","type":"network"},{"content":" Cisco IOS XR ","date":"18 July 2026","externalUrl":null,"permalink":"/en/routerswitch/","section":"Router and Switch Articles","summary":"","title":"Router and Switch Articles","type":"routerswitch"},{"content":"","externalUrl":null,"permalink":"/en/authors/","section":"Authors","summary":"","title":"Authors","type":"authors"},{"content":"","externalUrl":null,"permalink":"/posts/","section":"Posts","summary":"","title":"Posts","type":"posts"},{"content":"","externalUrl":null,"permalink":"/en/series/","section":"Series","summary":"","title":"Series","type":"series"},{"content":"","externalUrl":null,"permalink":"/en/tags/","section":"Tags","summary":"","title":"Tags","type":"tags"}]